A couple of links of possible relevance

[oursin]

An article on polari (which one feels Holmes would have been familiar with in its late C19th version, even if he didn't use it himself).

A digital version of John Addington Symonds' A Problem in Modern Ethics being an inquiry into the phenomenon of sexual inversion, addressed especially to Medical Psychologists and Jurists has recently been made available via Project Gutenberg, which has already done the same with A Problem in Greek Ethics, Being an inquiry into the phenomenon of sexual inversion. Sean Brady (author of Masculinity and Male Homosexuality in Britain, 1861 - 1913) is said to be producing a critical edition of Symonds' essays on homosexuality, but I don't think this has yet appeared.