Revenue recognized during 2020, 2019 & 2018 was from collaboration agreements with GlaxoSmithKline Intellectual Property Development Ltd (“GlaxoSmithKline”), Eli Lilly and Company (“Eli Lilly”), Genentech, Inc. (“Genentech”) and MedImmune LLC, a wholly owned subsidiary of AstraZeneca plc (“MedImmune”).

	2020 £’000		2019 £’000		2018 £’000
GlaxoSmithKline		6,356		5,753		6,079
Eli Lilly		3,522		819		8,561
Genentech		20,236		19,097		1,461
MedImmune		-		-		7,553
		30,114		25,669		23,654

United Kingdom	6,356	5,753	6,079
United States	23,758	19,916	17,575
	30,114	25,669	23,654

The following tables presents changes in the Group’s trade receivables, contract assets and contract liabilities during the year ended December 31, 2020 and 2019.

	At 1 January 2020 £’000		Additions £’000		Deductions £’000			At December 31, 2020 £’000
Trade receivables:
Trade receivables		1,186		4,023		(5,209	)		-
Total receivables		1,186		4,023		(5,209	)		-
Contract assets:
Contract assets		424		1,658		-			2,082
Total contract assets		424		1,658		-			2,082
Contract liabilities:
Deferred revenue		76,418		-		(24,432	)		51,986
Total contract liabilities		76,418		-		(24,432	)		51,986

	At 1 January 2019 £’000		Additions £’000		Deductions £’000			At December 31, 2019 £’000
Trade receivables:
Trade receivables		3,600		3,431		(5,845	)		1,186
Total receivables		3,600		3,431		(5,845	)		1,186
Contract assets:
Contract assets		-		424		-			424
Total contract assets		-		424		-			424
Contract liabilities:
Deferred revenue		98,232		-		(21,814	)		76,418
Total contract liabilities		98,232		-		(21,814	)		76,418

No revenue was recognized in 2020, 2019 or 2018 relating to performance obligations satisfied in previous years.

	2020 £’000		2019 £’000
Current deferred revenue (Note 23)		27,118		28,457
Non-current deferred revenue (Note 19)		24,868		47,961
		51,986		76,418