Disclosure Of Interests In Other Entities [Text Block]
| Concept | 2023-12-31 to 2024-12-28 | 2023-12-31 to 2024-12-28 | 2023-12-31 to 2024-12-28 | As at 2024-12-28 | 2023-12-31 to 2024-12-28 | 2023-01-01 to 2023-12-30 | 2023-01-01 to 2023-12-30 | 2023-01-01 to 2023-12-30 | As at 2023-12-30 | 2023-01-01 to 2023-12-30 | As at 2022-12-31 | 
|---|---|---|---|---|---|---|---|---|---|---|---|
| Disclosure of interests in other entities [text block] | — | — | — | — | — | — | — | — | — | — | — | 
| Disclosure of interests in subsidiaries [text block] | — | — | — | — | — | — | — | — | — | — | — | 
| Disclosure of subsidiaries [text block] | — | — | — | — | — | — | — | — | — | — | — | 
| Disclosure of subsidiaries [abstract] | |||||||||||
| Disclosure of subsidiaries [line items] | |||||||||||
| Current assets | — | — | — | 
                                                30,800,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | — | — | — | — | 
                                                26,000,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | — | — | 
| Non-current assets | — | — | — | 
                                                29,500,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | — | — | — | — | 
                                                30,400,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | — | — | 
| Current liabilities | — | — | — | 
                                                22,300,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | — | — | — | — | 
                                                21,600,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | — | — | 
| Non-current liabilities | — | — | — | 
                                                400,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | — | — | — | — | 
                                                200,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | — | — | 
| Revenue | — | — | 
                                                96,000,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | — | — | — | — | 
                                                88,000,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | — | — | — | 
| Profit (loss) | 
                                                -
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                -
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                3,600,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | — | 
                                                3,600,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                -
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                2,700,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                2,700,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | — | 
                                                -
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | — | 
| Comprehensive income | 
                                                -
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                -
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                3,600,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | — | 
                                                3,600,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                -
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                2,700,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                2,700,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | — | 
                                                -
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | — | 
| Disclosure of interests in associates [text block] | — | — | — | — | — | — | — | — | — | — | — | 
| Disclosure of associates [text block] | — | — | — | — | — | — | — | — | — | — | — | 
| Disclosure of associates [abstract] | |||||||||||
| Disclosure of associates [line items] | |||||||||||
| Profit (loss) from continuing operations | — | — | 
                                                2,800,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | — | — | — | — | 
                                                2,700,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | — | — | — | 
| Profit (loss) from discontinued operations | — | — | 
                                                800,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | — | — | — | — | 
                                                -
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | — | — | — | 
| Other comprehensive income | — | — | 
                                                -
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | — | — | — | — | 
                                                -
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | — | — | — | 
| Disclosure of interests in joint arrangements [text block] | — | — | — | — | — | — | — | — | — | — | — | 
| Disclosure of joint ventures [text block] | — | — | — | — | — | — | — | — | — | — | — | 
| Disclosure of joint ventures [abstract] | |||||||||||
| Disclosure of joint ventures [line items] | |||||||||||
| Cash and cash equivalents | — | — | — | 
                                                10,900,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | — | — | — | — | 
                                                10,700,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | — | 
                                                27,000,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
| Interest income | — | — | 
                                                400,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | — | — | — | — | 
                                                700,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | — | — | — | 
| Tax expense (income) | — | — | 
                                                1,700,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | — | — | — | — | 
                                                400,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | — | — | — |