Fair values of financial assets and liabilities - Schedule of Derivatives (Details) - GBP (£) £ in Millions |
Dec. 31, 2025 |
Dec. 31, 2024 |
|---|---|---|
| FINANCIAL INSTRUMENTS (Details) - Schedule of Derivatives [Line Items] | ||
| Derivative financial instruments | £ 19,727 | £ 24,065 |
| Derivative liabilities | (16,132) | (21,676) |
| Level 1 £m | ||
| FINANCIAL INSTRUMENTS (Details) - Schedule of Derivatives [Line Items] | ||
| Derivative financial instruments | 57 | 103 |
| Derivative liabilities | (29) | (79) |
| Level 2 £m | ||
| FINANCIAL INSTRUMENTS (Details) - Schedule of Derivatives [Line Items] | ||
| Derivative financial instruments | 19,206 | 23,221 |
| Derivative liabilities | (15,879) | (21,175) |
| Level 3 £m | ||
| FINANCIAL INSTRUMENTS (Details) - Schedule of Derivatives [Line Items] | ||
| Derivative financial instruments | 464 | 741 |
| Derivative liabilities | £ (224) | £ (422) |