VALUE OF IN-FORCE BUSINESS (Details) - Schedule of Acquired Value of In-Force Non-Participating Investment Contracts - Life and Annuity Insurance Product Line [Member] - In-Force [Member] - Nonparticipating Life Insurance Contract [Member] - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
VALUE OF IN-FORCE BUSINESS (Details) - Schedule of Acquired Value of In-Force Non-Participating Investment Contracts [Line Items]
Beginning Balance	£ 271	£ 306
Acquisition of business	6	5
Amortisation taken to income statement (note 11)	(30)	(40)
Ending Balance	£ 247	£ 271