v3.26.1
FINANCIAL INSTRUMENTS AND RELATED DISCLOSURES - Carrying value and fair value of financial instruments (Details) - Carrying value - Bonds - GBP (£)
£ in Millions
Jun. 30, 2026
Dec. 31, 2025
Carrying value and fair value of financial instruments    
Carrying value, Financial liabilities £ 7,380 £ 8,102
Fair value, Financial Liabilities £ 6,987 £ 7,730