[3] The majority of the Communist League argued against joining the ILP in favour of maintaining an open party, but allowed thirty of its members led by Denzil Dean Harber to form a secretive "Bolshevik-Leninist Fraction" in the ILP.
This difference in orientation essentially split the party, and in November 1934, sixty Trotskyist ILPers officially formed the Marxist Group.
By the ILP Conference of 1935, it claimed a similar strength to the Revolutionary Policy Committee, which was sympathetic to the Communist Party of Great Britain.
The Marxist Group soon realised that the ILP did not have mass influence outside Glasgow, and sent John Archer to check the actual strength of the party around the country.
Trotsky proposed drawing up a manifesto around a militant programme, including a call for a Fourth International, and requesting signatures to see how much influence the Group had.