v3.25.2
Other reserves - Narrative (Details) - GBP (£)
£ in Millions
 6 Months Ended 12 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Dec. 31, 2024
Disclosure of reserves within equity [line items]      
Other reserves £ (953)   £ (1,302)
Currency translation reserve      
Disclosure of reserves within equity [line items]      
Other reserves 2,038   3,690
Increase (decrease) in equity (1,652)   (93)
Fair value through other comprehensive income reserve      
Disclosure of reserves within equity [line items]      
Other reserves (1,316)   (1,681)
Increase (decrease) in equity 365 £ (474)  
Gains (losses) on changes in fair value 427 (522)  
Net gains (losses) transferred to net profits (82) 134  
Tax charge (credit) 141 (181)  
Cash flow hedging reserve      
Disclosure of reserves within equity [line items]      
Other reserves (1,333)   (2,448)
Increase (decrease) in equity 1,115 447  
Gains (losses) on changes in fair value 911 (1,142)  
Net gains (losses) transferred to net profits (628) (1,699)  
Tax charge (credit) 431 154  
Own credit reserve      
Disclosure of reserves within equity [line items]      
Other reserves (540)   (1,059)
Increase (decrease) in equity 519 (819)  
Tax charge (credit) 194 (309)  
Gain (loss) on change in value of foreign currency basis spreads, before tax 709 £ (1,131)  
Other reserves      
Disclosure of reserves within equity [line items]      
Other reserves £ 198   £ 196