Commitments - Narrative (Detail) - GBP (£) £ in Millions	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2017
Disclosure of Commitments [Abstract]
Capital expenditure on intangibles and property, plant and equipment	£ 255	£ 161	£ 84

The amount of future capital expenditures that the entity is committed to make.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2018-01-01
-Paragraph 112
-Subparagraph c
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2018-03-01&anchor=para_112_c&doctype=Standard
-URIDate 2018-03-16

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