RELATED PARTY TRANSACTIONS (Details) - Schedule of Compensation of Key Management Personnel - GBP (£) £ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Compensation
Salaries and other short-term benefits	£ 15	£ 14	£ 13
Share-based payments	15	18	22
Total compensation	£ 30	£ 32	£ 35

The amount of compensation to key management personnel in the form of share-based payments. [Refer: Key management personnel of entity or parent [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 24
-IssueDate 2019-01-01
-Paragraph 17
-Subparagraph e
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=24&code=ifrs-tx-2019-en-r&anchor=para_17_e&doctype=Standard
-URIDate 2019-03-27

Name:	ifrs-full_KeyManagementPersonnelCompensationSharebasedPayment
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration