v3.26.1
Net finance costs (Details)
£ in Millions, € in Billions
 6 Months Ended 12 Months Ended
Jun. 30, 2026
GBP (£)
Jun. 30, 2025
GBP (£)
Dec. 31, 2025
EUR (€)
Dec. 31, 2021
EUR (€)
Bond
Disclosure of attribution of expenses by nature to their function [line items]        
Net finance costs £ (403.0) £ (969.0)    
FV loss on derivatives £ 0.0 £ 4.0    
Proportion of average cost of debt 4.90% 5.10%    
Coupon on perpetual hybrid bonds net of tax £ (28.0) £ (22.0)    
BAT Plc        
Disclosure of attribution of expenses by nature to their function [line items]        
Number of perpetual hybrid bonds issued | Bond       2
Perpetual hybrid bonds | €     € 1.2 € 1.0
Perpetual hybrid bond repurchased | €     € 1.0  
Reported at CC        
Disclosure of attribution of expenses by nature to their function [line items]        
Net finance costs £ (806.0) (871.0)    
Percentage increase in net finance cost (7.50%)      
Canada        
Disclosure of attribution of expenses by nature to their function [line items]        
Net finance costs £ (54.0) (59.0)    
Interest related to FII GLO 10.0      
Venezuela        
Disclosure of attribution of expenses by nature to their function [line items]        
Gains (losses) on net monetary position 139.0      
Brazil        
Disclosure of attribution of expenses by nature to their function [line items]        
Credit in respect of Romania's other taxes 6.0 3.0    
Indonesia        
Disclosure of attribution of expenses by nature to their function [line items]        
Additional provisions, other provisions 2.0 0.0    
Netherlands        
Disclosure of attribution of expenses by nature to their function [line items]        
Interest expense 5.0 3.0    
FII GLO        
Disclosure of attribution of expenses by nature to their function [line items]        
Interest income (expense) 315.0      
Interest related to FII GLO £ 0.3 £ 19.0    
British Pound        
Disclosure of attribution of expenses by nature to their function [line items]        
Increase in exchange rate 1.40%