Revenue from contracts with customers - Revenue derived from entities accounting for more than 10 of revenue (Details) - GBP (£) £ in Thousands	12 Months Ended
Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2023
Revenue from contracts with customers
Revenue from contracts with customers	£ 666,514	£ 661,755	£ 648,401
Customer A
Revenue from contracts with customers
Revenue from contracts with customers	141,095	161,098	178,118
Customer B
Revenue from contracts with customers
Revenue from contracts with customers	£ 87,877	£ 90,051	£ 76,169

The amount of revenue from contracts with customers. A customer is a party that has contracted with an entity to obtain goods or services that are an output of the entity’s ordinary activities in exchange for consideration.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 15
-IssueDate 2024-01-01
-Paragraph 114
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=15&code=ifrs-tx-2024-en-r&anchor=para_114&doctype=Standard
-URIDate 2024-03-27

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 15
-IssueDate 2024-01-01
-Paragraph 113
-Subparagraph a
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=15&code=ifrs-tx-2024-en-r&anchor=para_113_a&doctype=Standard
-URIDate 2024-03-27

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