Disclosure Of Earnings Per Share [Text Block]
| Concept | 
                                    
                                        2024-04-01 to 2025-03-31  | 
                            
                                
                                    
                                        2024-04-01 to 2025-03-31  | 
                            
                                
                                    
                                        2023-04-01 to 2024-03-31  | 
                            
                                
                                    
                                        2023-04-01 to 2024-03-31  | 
                            
                        
|---|---|---|---|---|
| Disclosure of earnings per share [text block] | 
                                        
                                             | 
                                
                                    — | — | — | 
| Earnings per share [text block] | — | — | — | — | 
| Earnings per share [abstract] | ||||
| Earnings per share [line items] | ||||
| Basic earnings per share [abstract] | ||||
| Basic earnings (loss) per share from continuing operations | 
                                        
                                             
                                                0.7849
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                0.9423
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                0.8240
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                0.7123
                                                
                                             
                                        
                                     | 
                                
                            
| Diluted earnings per share [abstract] | ||||
| Diluted earnings (loss) per share from continuing operations | 
                                        
                                             
                                                0.7814
                                                
                                             
                                        
                                     | 
                                
                                    — | — | 
                                        
                                             
                                                0.7096
                                                
                                             
                                        
                                     | 
                                
                            
| Adjustments to reconcile profit (loss) to numerator used in calculating earnings per share [abstract] | ||||
| Profit (loss), attributable to owners of parent | 
                                        
                                             
                                                296,400,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | — | 
                                        
                                             
                                                268,800,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     | 
                                
                            
| Disclosure of depositary receipts [text block] | — | — | — | — | 
| Disclosure of depositary receipts [abstract] | ||||
| Disclosure of depositary receipts [line items] |