CONTINGENT LIABILITIES AND COMMITMENTS (Details) - Schedule of Operating Lease Commitments - GBP (£) £ in Millions	Dec. 31, 2018	Dec. 31, 2017
CONTINGENT LIABILITIES AND COMMITMENTS (Details) - Schedule of Operating Lease Commitments [Line Items]
Operating lease commitments	£ 2,043	£ 2,054
Not later than one year [member]
CONTINGENT LIABILITIES AND COMMITMENTS (Details) - Schedule of Operating Lease Commitments [Line Items]
Operating lease commitments	259	275
Later than one year and not later than five years [member]
CONTINGENT LIABILITIES AND COMMITMENTS (Details) - Schedule of Operating Lease Commitments [Line Items]
Operating lease commitments	807	845
Later than five years [member]
CONTINGENT LIABILITIES AND COMMITMENTS (Details) - Schedule of Operating Lease Commitments [Line Items]
Operating lease commitments	£ 977	£ 934

The amount of future minimum lease payments payable under non-cancellable operating leases. Minimum lease payments are payments over the lease term that the lessee is or can be required to make, excluding contingent rent, costs for services and taxes to be paid by, and reimbursed to, the lessor, together with: (a) for a lessee, any amounts guaranteed by the lessee or by a party related to the lessee; or (b) for a lessor, any residual value guaranteed to the lessor by: (i) the lessee; (ii) a party related to the lessee; or (iii) a third party unrelated to the lessor that is financially capable of discharging the obligations under the guarantee.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Note Expiry date 2019-01-01
-Name IAS
-Number 17
-IssueDate 2018-01-01
-Paragraph 35
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=17&date=2018-03-02&anchor=para_35_a&doctype=Standard&book=b
-URIDate 2018-03-16

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