Disclosure Of Property, Plant And Equipment [Text Block]
| Concept | 
                                    
                                        As at 2025-03-31  | 
                            
                                
                                    
                                        2024-04-01 to 2025-03-31  | 
                            
                                
                                    
                                        As at 2024-03-31  | 
                            
                        
|---|---|---|---|
| Disclosure of property, plant and equipment [text block] | — | 
                                        
                                             | 
                                
                                    — | 
| Disclosure of detailed information about property, plant and equipment [text block] | — | — | — | 
| Disclosure of detailed information about property, plant and equipment [abstract] | |||
| Disclosure of detailed information about property, plant and equipment [line items] | |||
| Reconciliation of changes in property, plant and equipment [abstract] | |||
| Property, plant and equipment | 
                                        
                                             
                                                283,200,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | 
                                        
                                             
                                                236,800,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             
                                        
                                     |