OTHER RESERVES - Schedule of Foreign Currency Translation Reserve (Details) - Reserve of change in value of foreign currency basis spreads - GBP (£) £ in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Foreign currency translation reserve
At 1 January	£ (159)	£ (176)	£ (164)
Currency translation differences arising in the year	(39)	4	(12)
At 31 December	(198)	(159)	(176)
Pre-tax
Foreign currency translation reserve
Net income statement transfers	£ 0	£ 13	£ 0

The gains (losses) recognised in other comprehensive income on exchange differences on the translation of financial statements of foreign operations, before tax, before reclassification adjustments. [Refer: Other comprehensive income]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2021-01-01
-Paragraph 91
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2021-en-r&anchor=para_91_b&doctype=Standard
-URIDate 2021-03-24

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