Share-based payments - Additional information (Details)	Jun. 30, 2026 Options £ / shares	Dec. 31, 2025 Options £ / shares
2021 Incentive Plan
Share-based payments
Number of options exercisable \| Options	2,792,941	1,727,449
2021 Incentive Plan \| Minimum
Share-based payments
Exercise price of share options exercisable	£ 0	£ 0
2021 Incentive Plan \| Maximum
Share-based payments
Exercise price of share options exercisable	£ 8.76	£ 8.92
EMI Scheme
Share-based payments
Number of options exercisable \| Options	672,961	676,571
Exercise price of share options exercisable	£ 1.73	£ 1.7

The weighted average exercise price of share options exercisable in a share-based payment arrangement. [Refer: Weighted average [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 2
-IssueDate 2025-01-01
-Paragraph 45
-Subparagraph b
-Clause vii
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=2&code=ifrs-tx-2025-en-r&anchor=para_45_b_vii&doctype=Standard
-URIDate 2025-03-27

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
-Name IFRS
-Number 19
-IssueDate 2025-01-01
-Paragraph 31
-Subparagraph b
-Clause vii
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=19&code=ifrs-tx-2025-en-r&anchor=para_31_b_vii&doctype=Standard
-URIDate 2025-03-27

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
-Name IFRS
-Number 19
-IssueDate 2025-01-01
-Paragraph 31
-Subparagraph b
-Clause vii
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=19&code=ifrs-tx-2025-en-r&anchor=para_31_b_vii&doctype=Standard
-URIDate 2025-03-27

Name:	ifrs-full_WeightedAverageExercisePriceOfShareOptionsExercisableInSharebasedPaymentArrangement2019
Namespace Prefix:	ifrs-full_
Data Type:	dtr-2022:perShareItemType
Balance Type:	na
Period Type:	instant