Contract liabilities - Summary of contract liabilities (Details) - GBP (£) £ in Millions	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2022
Contract liabilities [abstract]
Current	£ 127	£ 252
Non-current	2,119	1,754
Total contract liabilities	£ 2,246	£ 2,006	£ 1,472

The amount of an entity’s obligation to transfer goods or services to a customer for which the entity has received consideration (or the amount is due) from the customer.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 15
-IssueDate 2023-01-01
-Paragraph 105
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=15&code=ifrs-tx-2023-en-r&anchor=para_105&doctype=Standard
-URIDate 2023-03-23

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 15
-IssueDate 2023-01-01
-Paragraph 116
-Subparagraph a
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=15&code=ifrs-tx-2023-en-r&anchor=para_116_a&doctype=Standard
-URIDate 2023-03-23

+ Details

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Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- References

No definition available.

+ Details

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Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of current contract liabilities. [Refer: Contract liabilities]

+ References

+ Details

Name:	ifrs-full_CurrentContractLiabilities
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The amount of non-current contract liabilities. [Refer: Contract liabilities]

+ References

+ Details

Name:	ifrs-full_NoncurrentContractLiabilities
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant