RELATED PARTY TRANSACTIONS (Details) - Schedule of Compensation of Key Management Personnel - GBP (£) £ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Compensation
Salaries and other short-term benefits	£ 13	£ 17	£ 14
Share-based payments	22	23	18
Total compensation	£ 35	£ 40	£ 32

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 2016-01-13
-Paragraph 17
-Subparagraph e
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=24&date=2016-03-30&anchor=para_17_e&doctype=Standard
-URIDate 2016-03-31

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