Polari, the Lost Gay English Dialect
slate.com
slate.com
I grew up listening to recordings of "Round the Horne" in the UK, which included two characters Julian & Sandy that chatted a little in Polari during their sketches. A bunch of Polari words and phrases have migrated into general UK slang — so it's not really a case of dying out… more migrating and changing — as languages & dialects often do.
http://www.bbc.co.uk/programmes/b00c7q4l/episodes/player
http://www.bbc.co.uk/programmes/b00bfvkd/episodes/player
Liverpool's Maritime Museum has an insightful exhibit on gay life at sea; the exhibit includes a section on the polari:
http://www.liverpoolmuseums.org.uk/maritime/visit/floor-plan...
Edit: The classic Julian and Sandy sketches were recorded between 1965 and 1968. The last one was a reunion in 1987, shortly before Kenneth Williams' death.
What surprised me is how many words I use regualrly had their origins in Polari. I don't know whether it's because they've made their way into mainstream language, or just a regional thing though.
See: https://en.wikipedia.org/wiki/Trawling https://en.wikipedia.org/wiki/Trolling_(fishing)