CONSOLIDATED CASH FLOW STATEMENT (UNAUDITED) (Parenthetical) - GBP (£) £ in Millions	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020
Statement of cash flows [abstract]
Restricted cash and cash equivalents	£ 76	£ 84	£ 55

The amount of cash and cash equivalents whose use or withdrawal is restricted. [Refer: Cash and cash equivalents]

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2020-01-01
-Paragraph 55
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2020-en-r&anchor=para_55&doctype=Standard
-URIDate 2020-01-01

Name:	ifrs-full_RestrictedCashAndCashEquivalents
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant