v3.26.1
Cash flow - additional information (Details)
£ in Millions, $ in Millions
 6 Months Ended 12 Months Ended
Jun. 30, 2026
GBP (£)
Jun. 30, 2026
USD ($)
Jun. 30, 2025
GBP (£)
Jun. 30, 2025
USD ($)
Dec. 31, 2026
GBP (£)
Dec. 31, 2025
GBP (£)
Dec. 31, 2024
GBP (£)
Dec. 31, 2023
GBP (£)
Dec. 31, 2022
GBP (£)
Disclosure Of Cash Flow [Line Items]                  
Decrease in net cash generated from operating activities £ 1,093                
Income taxes paid, classified as operating activities 1,224   £ 1,576            
Research and development expense 188   174            
Net cash used in investing activities (300)   1,012            
Increase in net cash used in investing activities (1,312)                
Net proceeds from disposal of shares in associate, net of tax 0   1,052            
Purchase of short term investment products, including treasury bills 10   14            
Purchase of property, plant and equipment, classified as investing activities 134   103            
Purchase of property, plant and equipment, intangible assets other than goodwill, investment property and other non-current assets £ 163   140            
Decrease in purchases of property plant and equipment and intangibles 16.40% 16.40%              
Net cash used in financing activities £ (4,663)   (4,117)            
Outflow due to dividend payment 2,634   2,609            
Interest paid, classified as financing activities £ 905   £ 879            
Proportion of average cost of debt 4.90% 4.90% 5.10% 5.10%          
Net inflow (outflow) from borrowings £ (151)   £ 505            
Outflows relating to derivative financial instruments (39)   (445)            
Purchases of own shares 649   450            
Forecast                  
Disclosure Of Cash Flow [Line Items]                  
Purchase of property, plant and equipment, intangible assets other than goodwill, investment property and other non-current assets         £ 750        
Factoring of receivables                  
Disclosure Of Cash Flow [Line Items]                  
Amount factored 667   674            
Other payables 132   122            
ITG Brands                  
Disclosure Of Cash Flow [Line Items]                  
Credit in respect of settlement of historical litigations with ITG brands 149 $ 200 0            
US                  
Disclosure Of Cash Flow [Line Items]                  
Income taxes paid, classified as operating activities     491 $ 624          
US | 2024 to 2025                  
Disclosure Of Cash Flow [Line Items]                  
Tax payments deferred to subsequent period     700 895          
US | 2025 Q1 to 2025 Q2                  
Disclosure Of Cash Flow [Line Items]                  
Tax payments deferred to subsequent period     209 $ 271          
FII GLO                  
Disclosure Of Cash Flow [Line Items]                  
Payments (proceeds) in respect of litigation claim settlements 111   368            
Settlement payments 44         £ 479 £ 50 £ 50 £ 50
Interest paid on litigation settlements 67                
FII GLO | Forecast                  
Disclosure Of Cash Flow [Line Items]                  
Settlement payments         £ 222        
Engle Progeny Cases                  
Disclosure Of Cash Flow [Line Items]                  
Payments (proceeds) in respect of litigation claim settlements £ (2)   £ 42