On British telly in half an hour.

The US subtitles are indeed a thing:

Sparrows Can’t Sing attempts to represent the diversity of characters and cultures that were prevalent in the East End during the early 1960s, including those typically found in the local pub, as well as local tarts, Jewish tradesmen and spivs. Consequently the dialogue became a mix of rhyming slang, London Yiddish and thieves cant. It is no surprise that it became the first English language film to be released in the US with subtitles.

Also on the Internet Archive.