BORROWINGS - Committed credit facilities (Details) - GBP (£) £ in Millions	Jun. 30, 2026	Dec. 31, 2025
Disclosure of detailed information about borrowings [line items]
Borrowings	£ 8,252	£ 8,609
Credit facility maturing August 2029
Disclosure of detailed information about borrowings [line items]
Undrawn credit facilities	1,750
Borrowings	£ 0	£ 0

The amount of outstanding funds that the entity is obligated to repay.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Note Expiry date 2027-01-01
-Name IAS
-Number 1
-IssueDate 2025-01-01
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+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with members defined in one or many axes of the table.

+ References

No definition available.

+ Details

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- Definition

The amount of undrawn borrowing facilities that may be available for future operating activities and to settle capital commitments. [Refer: Capital commitments]

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Name IAS
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-IssueDate 2025-01-01
-Paragraph 50
-Subparagraph a
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=7&code=ifrs-tx-2025-en-r&anchor=para_50_a&doctype=Standard
-URIDate 2025-03-27

+ Details

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Balance Type:	credit
Period Type:	instant

- Details

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Namespace Prefix:
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Balance Type:
Period Type: