v3.26.1
Earnings per share - additional information (Details) - GBP (£)
£ / shares in Units, £ in Millions
6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Earnings Per Share [Line Items]    
Increase in basic earnings per share (28.60%)  
Basic (in GBP per share) £ 1.461 £ 2.046
Increase/(decrease) in adjusted diluted earnings per share 5.90%  
Adjusted diluted earnings per share (in GBP per share) £ 1.716 £ 1.620
Coupon on perpetual hybrid bonds net of tax £ (28) £ (22)
Share buy-back programme | Ordinary shares    
Earnings Per Share [Line Items]    
Shares brought back and cancelled 14,609,571  
FII GLO    
Earnings Per Share [Line Items]    
Interest income (expense) £ (315)  
Adjusting tax credit (debit) on litigation settlements £ 95  
ITC Hotels Limited    
Earnings Per Share [Line Items]    
Gains (losses) Arising From Difference Between Carrying Value And Fair Value, Net Of Tax, Demerger Operation   (333)
ITC Ltd.    
Earnings Per Share [Line Items]    
Adjustments for gain on disposal of investments in subsidiaries, joint ventures and associates   £ 904