Intergovernmental

UK membership of the League of Nations
(26 yrs) 1920 - 1946
Commonwealth of Nations
(93 yrs) 1931 - 2024
UK membership of the UN
(79 yrs) 1945 - 2024
UK membership of the UNSC
(79 yrs) 1945 - 2024
UK membership of the IMF
(79 yrs) 1945 - 2024
UK membership of NATO
(75 yrs) 1949 - 2024
UK membership of the EFTA
(13 yrs) 1960 - 1973
UK membership of the OECD
(63 yrs) 1961 - 2024
UK membership of the EEC/EU
(47 yrs) 1973 - 2020
UK membership of the G7
(48 yrs) 1976 - 2024
UK membership of the WTO
(29 yrs) 1995 - 2024
UK membership of the G20
(25 yrs) 1999 - 2024