Shawly not again
Enough with the Shaw already, this will be the last one - but it touches on the SPGB.
Or rather, it is Shaw discussing the SDF, but his discussion, I would affirm, puts the SPGB case elegently:
...[T]he Fabian society is a society for helping to bring about the Socialization of the industrial resources of the country. The Social Democratic Federation is a society for enlisting the entire proletariat of the country in its own ranks and itself Socializing the national industry. The Federation persistently claims to be the only genuinely representative of the working class interests in England. It counts no man a socialist until he has joined it, and supports no candidate who is not a member. If one of its speakers supports an outside candidate, he is disowned. Only the other day the Executive Council of the Federation proposed that no member should even vote for a candidate not enrolled within its ranks. The Federation chooses its own candidates without consulting its neighbours, and sends them to the poll, when it has the money, without the slightest regard to the possibilities of such a course making a present of the seat to the least Socialistic candidate in the field. This implacably sectarian policy depends for its success on the recruiting powers of the society that adopts it.Shaw's sole refutation is that such a mass recruitment is not plausible - fair enough, but since we have seen Fabianism fail -and hoist by its own Petard by Tony Blair's permeation of the Labour Party with Christian Democrat Fabians - it really does remain the only socialist game in town.
If the majority can be persuaded, the SDF/SPGB course is valid, if not, then the only option is indeed the Fabian tactic - after all, so long as people aren't anti-Socialist it may bring improvements.