RELATED PARTY TRANSACTIONS (Details) - Schedule of Compensation of Key Management Personnel - GBP (£) £ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Compensation
Salaries and other short-term benefits	£ 14	£ 13	£ 17
Share-based payments	18	22	23
Total compensation	£ 32	£ 35	£ 40

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 2018-01-01
-Paragraph 17
-Subparagraph e
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=24&date=2018-03-01&anchor=para_17_e&doctype=Standard
-URIDate 2018-03-16

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