Income Tax - Schedule of Major Components of Income Tax Assets (Detail) - GBP (£) £ in Thousands	Jun. 30, 2025	Dec. 31, 2024
Current income tax receivable
Current income tax receivable	£ 4,266	£ 4,594
Deferred tax asset
Deferred tax asset	112	113
U.K. [member]
Current income tax receivable
Current income tax receivable	4,263	4,591
U.S. [member]
Current income tax receivable
Current income tax receivable	3	3
Deferred tax asset
Deferred tax asset	£ 112	£ 113

The amounts of income taxes recoverable in future periods in respect of: (a) deductible temporary differences; (b) the carryforward of unused tax losses; and (c) the carryforward of unused tax credits. [Refer: Temporary differences [member]; Unused tax credits [member]; Unused tax losses [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 12
-IssueDate 2024-01-01
-Paragraph 81
-Subparagraph g
-Clause i
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-URIDate 2024-03-27

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2024-01-01
-Paragraph 54
-Subparagraph o
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2024-en-r&anchor=para_54_o&doctype=Standard
-URIDate 2024-03-27

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2024-01-01
-Paragraph 56
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2024-en-r&anchor=para_56&doctype=Standard
-URIDate 2024-03-27

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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