You've heard a load of rubbish then, Jonny. Several clubs in St James's are still men only. The rest which did admit women on special terms, or only allowed women visitors restricted service, fell foul of anti-discrimination law and had to treat women on equal terms. thereafter.
There are no initiation ceremonies ! The only requirements are that the candidate fits in, that he be proposed and seconded by existing members who know him, and, in some clubs, that he is not blackballed when his name is advertised as a candidate i.e, that no member objects to his becoming a member. Fitting in may be the hard part. Both the Carlton and Junior Carlton expect members to be Tories; they were founded to support what is now the Conservative party. The Turf expects you to have some keen interest in horse-racing and matters equine and Pratt's expects you to be a prat, though a well-bred one !