v3.26.1
Material accounting policies - Additional Information (Detail) - GBP (£)
£ in Thousands
6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Dec. 31, 2025
Dec. 31, 2024
Disclosure Of Summary Of Material Accounting Policies [Line Items]        
Accumulated deficit £ (253,749)   £ (252,334)  
Cash flows from (used in) operating activities (5,245) £ (7,595)    
Cash and cash equivalents £ 19,503 £ 8,443 £ 24,251 £ 6,749