Statement Of Financial Position [Abstract]
| Concept | 
                                    
                                        As at 2022-12-31  | 
                            
                                
                                    
                                        As at 2022-12-31  | 
                            
                                
                                    
                                        As at 2022-12-31  | 
                            
                                
                                    
                                        As at 2022-12-31  | 
                            
                                
                                    
                                        As at 2022-12-31  | 
                            
                                
                                    
                                        As at 2022-12-31  | 
                            
                                
                                    
                                        As at 2021-12-31  | 
                            
                                
                                    
                                        As at 2021-12-31  | 
                            
                                
                                    
                                        As at 2021-12-31  | 
                            
                                
                                    
                                        As at 2021-12-31  | 
                            
                                
                                    
                                        As at 2021-12-31  | 
                            
                                
                                    
                                        As at 2021-12-31  | 
                            
                                
                                    
                                        As at 2020-12-31  | 
                            
                                
                                    
                                        As at 2020-12-31  | 
                            
                                
                                    
                                        As at 2020-12-31  | 
                            
                                
                                    
                                        As at 2020-12-31  | 
                            
                                
                                    
                                        As at 2020-12-31  | 
                            
                                
                                    
                                        As at 2020-12-31  | 
                            
                        
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Statement of financial position [abstract] | ||||||||||||||||||
| Assets [abstract] | ||||||||||||||||||
| Property, plant and equipment | 
                                        
                                             
                                                2,999,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | — | — | — | — | 
                                        
                                             
                                                3,925,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | — | — | — | — | — | — | — | — | — | — | 
| Right-of-use assets | 
                                        
                                             
                                                6,834,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | — | — | — | — | 
                                        
                                             
                                                7,877,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | — | — | — | — | — | — | — | — | — | — | 
| Intangible assets other than goodwill | 
                                        
                                             
                                                2,886,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | — | — | — | — | 
                                        
                                             
                                                2,772,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | — | — | — | — | — | — | — | — | — | — | 
| Deferred tax assets | 
                                        
                                             
                                                -
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | — | — | — | — | 
                                        
                                             
                                                –
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | — | — | — | — | — | — | — | — | — | — | 
| Cash and cash equivalents | 
                                        
                                             
                                                32,783,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | — | — | — | — | 
                                        
                                             
                                                114,577,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | — | — | — | — | 
                                        
                                             
                                                77,956,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | — | — | — | — | 
| Assets | 
                                        
                                             
                                                223,969,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | — | — | — | — | 
                                        
                                             
                                                341,138,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | — | — | — | — | — | — | — | — | — | — | 
| Equity and liabilities [abstract] | ||||||||||||||||||
| Equity [abstract] | ||||||||||||||||||
| Issued capital | 
                                        
                                             
                                                15,621,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | — | — | — | — | 
                                        
                                             
                                                15,621,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | — | — | — | — | — | — | — | — | — | — | 
| Retained earnings | 
                                        
                                             
                                                293,441,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | — | — | — | — | 
                                        
                                             
                                                237,082,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | — | — | — | — | — | — | — | — | — | — | 
| Share premium | 
                                        
                                             
                                                180,019,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | — | — | — | — | 
                                        
                                             
                                                180,019,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | — | — | — | — | — | — | — | — | — | — | 
| Other reserves | 
                                        
                                             
                                                255,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | — | — | — | — | 
                                        
                                             
                                                255,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | — | — | — | — | — | — | — | — | — | — | 
| Equity | 
                                        
                                             
                                                97,546,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                –
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                180,019,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                293,441,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                15,621,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                255,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                41,187,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                237,082,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                255,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                180,019,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                –
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                15,621,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                11,536,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                207,727,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                –
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                15,621,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                551,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                180,019,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     | 
                                
                            
| Equity and liabilities | 
                                        
                                             
                                                223,969,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | — | — | — | — | 
                                        
                                             
                                                341,138,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | — | — | — | — | — | — | — | — | — | — |