Statement Of Changes In Net Assets Available For Benefits [Abstract]
| Concept | 2022-01-01 to 2022-12-31 | 2022-01-01 to 2022-12-31 | 2022-01-01 to 2022-12-31 | 2021-01-01 to 2021-12-31 | 2021-01-01 to 2021-12-31 | 2021-01-01 to 2021-12-31 | 
|---|---|---|---|---|---|---|
| Statement of changes in net assets available for benefits [abstract] | ||||||
| Reconciliation of changes in net assets available for benefits [abstract] | ||||||
| Changes in net assets available for benefits [abstract] | ||||||
| Administrative expenses | 
                                                –
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                1,19 1
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                1,1 91
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                –
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                1,164,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                1,164,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
| Tax expense (income) | 
                                                –
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                18,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                18,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                –
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                304,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                304,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             |