An "element of kink" is apparent in most vampire movies -- they're about people who suck blood, after all. Incest was a common enough practise among the aristocracy of yesteryear, history tells us, and it makes narrative sense for the Baroness Meinster to have availed her neck to her imprisoned son, rather than risk the scandal of having him run loose and ruining the family name. So, if anything, there is an incestuous kink to the film, rooted in class, and not really a gay one; the references to Baron Meinster's "revels" suggest something like his membership in a kind of orgiastic Hellfire Club, not an 18th century counterpart to the Village People. Mr. Peel is a very "pretty boy" sort of vampire, and I'm sure he set many young male hearts athrob in his day, but I don't remember anything in the film itself that points to the Baron's homosexual inclinations.

I also must question how "openly gay" anyone knows David Peel to have been. He seems to have eschewed interviews himself, and none of his colleagues have ever come forward with a definitive David Peel story, so I would imagine he was rather secretive about himself and his private life. I've heard, second-hand, a reminiscence of Peter Cushing that Mr. Peel arrived onset one day with a troika of pink poodles, but being second-hand, there's no way of telling if this was his form of a coded joke or if they were literal pets.