After the victory of the Bolshevik Revolution in Russia at the end of 1917 and the termination of the First World War the following year, the BSP emerged as an explicitly revolutionary socialist organisation.

The resulting organisation, the BSP, contained a multiplicity of views and was organized as a loose federation of clubs and branches rather than as a centralised and disciplined party.

This leading group advocated that the BSP place an emphasis on electoral politics and the effort to capture the state through the ballot box rather than through labour agitation, the formation of trade unions, and pursuit of an extra-parliamentary route to power via the strike movement.

This cautious, electoral orientation of Hyndman and the early BSP leadership put the party at odds with the tumultuous situation in workplaces around the country.

This executive was headed by Henry Hyndman one of the founders of the SDF, an individual who had grown steadily more nationalistic in viewpoint, coming to advocate for the increase of Britain's military budget to oppose potential German aggression.

[8] The 2nd Conference of the BSP of May 1913 did not resolve the fundamental question facing the party — the decision as to whether it should pursue a policy of anti-militarist internationalism, come what may, or whether it should rally around the flag in the event of military conflict with foreign enemies.

Many socialist organisations internationally split over the question to greater or lesser degree (an exception must be made for most anarchist and syndicalist groups, which were anti-war), into left-wing "internationalist" factions, which continued to seek the united action of the working class against worldwide capitalism without regard to territorial boundaries, and right-wing "defencists", who rallied to their national colors to defend their country in time of military conflict.

[9] Early in 1915 came the inevitable split, with the conservative Hyndman wing of the party leaving to form the Socialist National Defence League, while the leadership was defeated in elections in 1916 by an internationalist group, essentially pacifist, supporting the programme of the Zimmerwald Conference.

John Maclean, the party's leader in Scotland, was a revolutionary defeatist[10] who played a leading role in the Red Clydeside strikes during the First World War.

The party's new leadership, around Secretary Albert Inkpin, Treasurer Alf Watts, and key labour movement leader John Maclean maintained the desire to join the Second International.

Representatives of the BSP were J. F. Hodgson, A.A. "Alf" Watts, and Fred Willis, joined by Tom Bell, Arthur MacManus, and William Paul of the "Communist Unity Group" faction formerly associated with the SLP, as well as W. J. Hewlett of the SWCC.

The group agreed in advance that a Provisional Executive Committee should be established by the forthcoming Communist Party of Great Britain by the Convention electing six more to add to this list.