Disclosure Of Fair Value Measurement [Text Block]
| Concept | As at 2024-12-31 | As at 2024-12-31 | As at 2024-12-31 | As at 2024-12-31 | As at 2024-12-31 | As at 2024-12-31 | As at 2024-12-31 | As at 2023-12-31 | As at 2023-12-31 | As at 2023-12-31 | As at 2023-12-31 | As at 2023-12-31 | As at 2023-12-31 | As at 2023-12-31 | 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 2022-12-31 | As at 2022-12-31 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Disclosure of fair value measurement [text block] | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Disclosure of fair value measurement of assets [text block] | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Disclosure of fair value measurement of assets [abstract] | |||||||||||||||||||||
| Disclosure of fair value measurement of assets [line items] | |||||||||||||||||||||
| Assets | — | — | — | — | — | — | 
                                                346,300,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                451,300,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Reconciliation of changes in fair value measurement, assets [abstract] | |||||||||||||||||||||
| Disclosure of fair value measurement of liabilities [text block] | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Disclosure of fair value measurement of liabilities [abstract] | |||||||||||||||||||||
| Disclosure of fair value measurement of liabilities [line items] | |||||||||||||||||||||
| Liabilities | — | — | — | — | — | — | 
                                                260,400,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                213,800,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Reconciliation of changes in fair value measurement, liabilities [abstract] | |||||||||||||||||||||
| Disclosure of fair value measurement of equity [text block] | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Disclosure of fair value measurement of equity [abstract] | |||||||||||||||||||||
| Disclosure of fair value measurement of equity [line items] | |||||||||||||||||||||
| Equity | 
                                                1,600,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                52,200,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                133,700,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                18,900,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                16,500,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                400,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                85,900,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                237 .5
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                93,400,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                1,600,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                133,700,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                18. 9
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                13. 0
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                2 .9
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                223. 7
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                24,300,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                1,600,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                185,300,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                9 .4
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                800,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                3. 9
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
| Reconciliation of changes in fair value measurement, entity's own equity instruments [abstract] |