It should be noted that a century ago, homosexual acts between men and/or boys were illegal (Oscar Wilde) in most parts of the western world and if found out, you could be fined or imprisoned. So apart from court cases, it would be difficult to determine who was doing what back then.

I cannot answer specifically about a hundred years ago, but it might be interesting to look up the now disused Polari slang which was used in British theatre and also amongst merchant seaman and stewards and other passenger staff on cruise liners. In much the same way Cockney was a method for discussing borderline criminal activities without being understood by outsiders, Polari was used by gays for discussing other types of illegal activity. So it could be generalised that the British theatre and merchant navy accommodated many gays. It would take rather more digging to establish how much further this went back.

Btw Polari eventually entered the mainstream and was used by two characters, Julian and Sandy in a popular British Radio comedy show Round the Horne. Here is a good link from the Liverpool Maritime Museum discussing it and mentioning that it goes back to the 1900s on ships.