Earnings per share (Details) - GBP (£) £ / shares in Units, £ in Millions, shares in Millions	6 Months Ended
Jun. 30, 2025	Dec. 31, 2024	Jun. 30, 2024
Earnings per share [abstract]
Profit attributable to ordinary shareholders	£ 2,274	£ 1,778	£ 2,145
Weighted-average number of ordinary shares in issue – basic (in shares)	60,320	61,385	63,453
Adjustment for share options and awards (in shares)	739	329	600
Weighted-average number of ordinary shares in issue – diluted (in shares)	61,059	61,714	64,053
Basic earnings per share (in GBP per share)	£ 0.038	£ 0.029	£ 0.034
Diluted earnings per share (in GBP per share)	£ 0.037	£ 0.029	£ 0.033

The weighted average number of ordinary shares outstanding plus the weighted average number of ordinary shares that would be issued on the conversion of all the dilutive potential ordinary shares into ordinary shares. [Refer: Ordinary shares [member]; Weighted average [member]]

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The amount of profit (loss) attributable to ordinary equity holders of the parent entity (the numerator) divided by the weighted average number of ordinary shares outstanding during the period (the denominator).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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The amount of profit (loss) attributable to ordinary equity holders of the parent entity (the numerator), divided by the weighted average number of ordinary shares outstanding during the period (the denominator), both adjusted for the effects of all dilutive potential ordinary shares. [Refer: Ordinary shares [member]; Weighted average [member]]

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The potential dilutive effect on the weighted average number of ordinary shares that relate to the assumed exercise of the entity's share options.

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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The profit (loss) attributable to ordinary equity holders of the parent entity. [Refer: Profit (loss)]

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The number of ordinary shares outstanding at the beginning of the period, adjusted by the number of ordinary shares bought back or issued during the period multiplied by a time-weighting factor.

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