Retirement benefit obligations - Schedule of Movements in Other Post-Retirement Benefits Obligation (Details) - GBP (£) £ in Millions |
12 Months Ended | |
|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
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| RETIREMENT BENEFIT OBLIGATIONS (Details) - Schedule of Movements in Oher Post-Retirement Benefits Obligation [Line Items] | ||
| At 1 January | £ 2,906 | |
| At 31 December | 2,575 | £ 2,906 |
| Other post retirement benefit plans defined benefit | ||
| RETIREMENT BENEFIT OBLIGATIONS (Details) - Schedule of Movements in Oher Post-Retirement Benefits Obligation [Line Items] | ||
| At 1 January | (39) | (44) |
| Actuarial gains | 2 | 4 |
| Insurance premiums paid | 2 | 3 |
| Charge for the year | (2) | (2) |
| At 31 December | £ (37) | £ (39) |
| X | ||||||||||
- Definition The increase (decrease) in the net defined benefit liability (asset) resulting from employee service in the current period. [Refer: Net defined benefit liability (asset)] Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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| X | ||||||||||
- Definition The decrease (increase) in a net defined benefit liability (asset) resulting from the remeasurement of that net defined benefit liability (asset). [Refer: Net defined benefit liability (asset)] Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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| X | ||||||||||
- Definition The amount of deficit or surplus in a defined benefit plan, adjusted for any effect of limiting a net defined benefit asset to the asset ceiling. [Refer: Defined benefit plans [domain]] Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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| X | ||||||||||
- Definition Decrease In Net Defined Benefit Liability (Asset) Resulting From Insurance Premium Paid No definition available.
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| X | ||||||||||
- Definition RETIREMENT BENEFIT OBLIGATIONS (Details) - Schedule of Movements in Oher Post-Retirement Benefits Obligation [Line Items] No definition available.
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| X | ||||||||||
- Details
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