There’s this article on this

[ALB]

There’s this article on this site about “The Myth of a Transitional Society”. There is also an article on “The ‘Transition Period'” in the January 1946 Socialist Standard but this does seem to be on (yet?).As to the history of the SPGB, online are this,  this and this.There’s also this article but you have to register and pay to see it, so that’s no good then.And there’s this on the “impossibilists” of the Socialist Party of Canada.