Finance expense - Schedule Of Finance Cost Explanatory (Detail) - GBP (£) £ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Disclosure of instruments with potential future dilutive effect not included in calculation of diluted earnings per share [line items]
Revaluation loss from derivative financial instruments	£ 0	£ (12,648)	£ 0	£ (12,648)

The gain (loss) recognised on designation of a financial instrument, or a proportion of it, as measured at fair value through profit or loss, because a credit derivative is used to manage the credit risk of that financial instrument. [Refer: Credit risk [member]; Derivatives [member]; Classes of financial instruments [domain]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2025-01-01
-Paragraph 24G
-Subparagraph b
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2025-en-r&anchor=para_24G_b&doctype=Standard
-URIDate 2025-03-27

Name:	ifrs-full_GainLossOnDesignationOfFinancialInstrumentAsMeasuredAtFairValueThroughProfitOrLossBecauseCreditDerivativeIsUsedToManageCreditRisk
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration