I have collected almost 500 Polari terms, although it's unlikely that most people would have known or even used that many.
However, it has also been used in the past by Julian Clary, Larry Grayson, Peter Wyngarde, and in a Jon Pertwee episode of Dr Who (Carnival of Monsters). The most famous users of Polari were Julian and Sandy (played by Hugh Paddick and Kenneth Williams) in the 1960s BBC radio comedy show, Round The Horne (written by Barry Took and Marty Feldman). Straight people who were connected to the theatre also used it, and there are numerous cases of gay men teaching it to their straight friends. Mainly gay men, although also lesbians, female impersonators, theatre people, prostitutes and sea-queens (gay men in the merchant navy). In 2010, Cambridge University labelled Polari as an "endangered language". While it was mainly used as a lexicon, some of the more adept speakers were so good at it, that it resembled a language, with its own grammatical rules, distinct to English. Polari can be classed as a language variety, a sociolect, or an anti-language. Some of the most common include rhyming slang, backslang (saying a word as if it's spelt backwards), Italian, Occitan, French, Lingua Franca, American airforce slang, drug-user slang, Parlyaree (an older form of slang used by tinkers, beggars and travelling players) and Cant (an even older form of slang used by criminals). It is mainly a lexicon, derived from a variety of sources. In the past, it was also known as Palari, Palare, Parlaree or a variety of similar spellings.
Paul Baker, Linguistics and English Language, Lancaster University Polari: The Lost Language of Gay Men What is Polari?