Annual and transition report of foreign private issuers pursuant to Section 13 or 15(d)

Intangible assets and goodwill (Details)

v3.23.1
Intangible assets and goodwill (Details) - GBP (£)
 12 Months Ended
Dec. 31, 2022
Dec. 31, 2021
Intangible assets and goodwill (Details) [Line Items]    
Contractor development expenditure (in Pounds) £ 15,800,000 £ 11,100,000
Other long term (in Pounds) 2,000  
Impairment (in Pounds) 157,800,000  
UK [Member]    
Intangible assets and goodwill (Details) [Line Items]    
Recoverable amount (in Pounds) £ 491,200,000 £ 1,658,600,000
Percentage of pre-tax discount rate 21.30% 15.70%
Growth rate percentage 2.00% 2.00%
Impairment charge (in Pounds) £ 136,700,000 £ 1,004,700,000
Cash flow projection period 7 years  
Gross margin percentage 1.00%  
Growth rate percentage 1.00%  
Cazana [Member]    
Intangible assets and goodwill (Details) [Line Items]    
Recoverable amount (in Pounds) £ 2,700,000 £ 4,600,000
Percentage of pre-tax discount rate 18.10% 23.30%
Growth rate percentage 2.00% 2.00%
Impairment charge (in Pounds)   £ 5,500,000
Headroom (in Pounds) £ 1,000,000  
Gross margin percentage 1.00%  
Terminal Growth Rate [Member]    
Intangible assets and goodwill (Details) [Line Items]    
Impairment (in Pounds) £ 26,900,000  
Terminal Growth Rate [Member] | Cazana [Member]    
Intangible assets and goodwill (Details) [Line Items]    
Growth rate percentage 1.00%  
Discount Rates [Member]    
Intangible assets and goodwill (Details) [Line Items]    
Additional impairment charge (in Pounds) £ 54,600,000  
Discount Rates [Member] | UK [Member]    
Intangible assets and goodwill (Details) [Line Items]    
Percentage of pre-tax discount rate 1.00%  
Discount rates percentage 22.30%  
Discount Rates [Member] | Cazana [Member]    
Intangible assets and goodwill (Details) [Line Items]    
Percentage of pre-tax discount rate 10.80%  
Discount rates percentage 28.90%