Statement Of Cash Flows [Abstract]
| Concept | 2022-01-01 to 2022-12-31 | 2021-01-01 to 2021-12-31 | 
|---|---|---|
| Statement of cash flows [abstract] | ||
| Cash flows from (used in) operating activities [abstract] | ||
| Adjustments for finance income | 
                                                39,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                4,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
| Cash flows from (used in) operations before changes in working capital | 
                                                4,168,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                4,153,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
| Adjustments for decrease (increase) in trade and other receivables | 
                                                1,732,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                391,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
| Adjustments for increase (decrease) in trade and other payables | 
                                                34,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                120,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
| Adjustments for gains (losses) on fair value adjustment, investment property | 
                                                10,381,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                8,755,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
| Finance costs paid, classified as operating activities | 
                                                840,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                855,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
| Finance income received, classified as operating activities | 
                                                39,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                4,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
| Cash flows from (used in) investing activities [abstract] | ||
| Purchase of investment property | 
                                                726,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                –
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
| Proceeds from sales of investment property | 
                                                –
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             | 
                                                1,925,000
                                                
                                                    
                                                        GBP
                                                    
                                                
                                             |