v3.26.1
Financial instruments - Additional Information (Details)
$ / shares in Units, £ in Thousands
6 Months Ended
Apr. 20, 2026
D
$ / shares
Dec. 15, 2021
USD ($)
Jun. 30, 2026
GBP (£)
shares
Jun. 30, 2026
USD ($)
shares
Dec. 31, 2025
GBP (£)
Dec. 31, 2025
USD ($)
Disclosure of financial liabilities [line items]            
Aggregate purchase price | £     £ 7,719      
Convertible Senior Secured Notes            
Disclosure of financial liabilities [line items]            
Principal amount outstanding       $ 165,364,000   $ 146,286,000
Aggregate purchase price   $ 192,000,000        
Series A Convertible Preferred Shares            
Disclosure of financial liabilities [line items]            
Financial liabilities, at fair value | £     1,799      
Series A Convertible Preferred Shares | YA II PN, Ltd. ("Yorkville") | Securities Purchase Agreement            
Disclosure of financial liabilities [line items]            
Fixed conversion price on initial tranche of offering (in dollars per share) | $ / shares $ 3.588          
Fixed conversion price on subsequent tranches of offering (% of closing sale price) 120.00%          
Percentage of VWAP of ordinary shares (in%) 96.00%          
Number of consecutive trading days immediately preceding the conversion date | D 5          
Floor conversion price (in dollars per share) | $ / shares $ 0.598          
Outstanding aggregate stated value       2,000,000    
Convertible Senior Secured Notes            
Disclosure of financial liabilities [line items]            
Convertible Senior Secured Notes principal amount       $ 1,000    
Financial liabilities, at fair value | £     £ 91,271   £ 188,526  
Convertible Senior Secured Notes | First half of principal amount            
Disclosure of financial liabilities [line items]            
Conversion rate (in shares) | shares     285.714 285.714    
Convertible Senior Secured Notes | Interest paid in-kind and semi-annually in arrears            
Disclosure of financial liabilities [line items]            
Interest rate (in percent)     12.00% 12.00%    
Convertible Senior Secured Notes | Interest paid in cash            
Disclosure of financial liabilities [line items]            
Interest rate (in percent)     10.00% 10.00%