Jeremy Corbyn, pictured in 1984, continued to write for the Socialist Organiser even after it said many people were sorry the Brighton bombing had not killed Margaret Thatcher

Jeremy Corbyn and John McDonnell were little-known backbenchers when they took the helm of the Labour Party in 2015, but they have long been leading lights in the obscure sects of the far left.

Their decades of activism have been previously uncovered in records of the Morning Star communist newspaper at the British Library, the political collections held by the London School of Economics, and the Greater London Council files at the London Metropolitan Archives.

Now The Times has uncovered a new trove of material about them in the archive of “Trotskyite and other Left-wing pamphlets and publications” kept by Warwick University. Yellowing pages record how both men courted Socialist Organiser, a newspaper dedicated to turning Labour into a hard-left party in the wake