Since such a group is based on common interests, those interests work both as a filter (whoever is not interested will not apply) and as an admission requirement (if you don’t share those interests, you may be denied admission). As long as the common interest is not of sexual nature, neither need the admission criteria be. The group is exclusive with respect to the shared interests of its members, not their inherent features. Anyway, I am far from the idea that a men's club is “in se” a mysoginous thing - indeed men may share interests they do not have in common with women. However, men are not all the same and sexual behaviour is just one thing they may not all share, although they may have many other things in common. What one does in bed is a private matter and I am sure it is not a subject of discussion among gentlemen in clubs.
NJS, I don’t know if anyone felt insulted and I am not advocating any cause here - my reference to Wilde was meant as to someone who was persecuted (and prosecuted) on account of his nature (he certainly was not imprisoned because he sired two sons), therefore a victim of society (unless you think he was a victim of his own conduct). The laws may have changed since then, but unjustified social exclusion continues to take place. I agree, however, that it is not non-discrimination laws that will solve this (they sometimes have the contrary effect, as you wrote), but a better understanding of human variability.
Perhaps I am more idealistic (or naive) on account of my youth and my discourse is purely theoretical as I am not a member of any London club
