POD: Dewey Defeats Truman (actually).
Dewey gives into the neo-isolationst wing of the Republican Party. Marshall aid is stopped cold. USA reverts to semi-isolationism. No NATO, limited participation in UN.
The cut-off of Marshall aid hammers the battered European industrial economies. Europeans exploit to their colonial empires for economic succor. Britain still looses India, but iron-grips everything else. French and Belgians get even worse in Africa and the bits of Asia they own. Residents in the NEI start to miss the Japanese.
In the 1950s, European communist movements are brutally suppressed. European neo-colonialist movements spring up everywhere as all of Europe turns into a larger version of Weimar Germany circa 1931. Churchill assassinated in 1953; hard-right parties come to power in UK, France, Benelux and Italy. Overtures to Franco, FRG. Europeans form European Defense Community (EDC) in 1954. France, UK explode nukes. Bluntly tell Soviets to mind their own business. Stalin and successor happy to recover in peace - plan to strike the Europeans later.
Brutal, vicious, unending series of colonial wars - Algeria, Nigeria, Congo, NEI, Burma. Australia, NZ, Canada withdraw from Commonwealth; South Africa enthusiaticalluy particpates for larger share of Britain's African pie. European society completely militarized. Alliance with Israel; Israeli/EDC control of Suez, Saudi. No Berlin Wall - no need as West Germany every bit as nasty as east.
Great Awakening in USA. JFK elected in 1968, ending 20 years of Republican rule. Military build up in USA. Mass protests about European colonialism.
1969: Iceland Missile Crisis. Dispute between Icelandic and British fishermen erupts. USA backs Iceland. Stations USN squadron at Rekjavik. Installs medium-range missiles in Iceland. Brits furious. US population largely supportive (reverse of OTL; with no Vietnam or Korea, there is no anti-government feeling, and just as much rage. In this TL, it is directed at European colonialism).
Brits demand removal of US missiles from Iceland. US tells them to get stuffed. EDC mobalizes and announces RN 'blockade' of Iceland. USN gathers in Norfolk and sorties, JFK proclaims blockade will be lifted or destroyed...
Mike