Stackridge released five records between 1971 and 1976. Prog mixed with British folk-rock sounds well nigh impossible, but that is what they sound like. The Man In The Bowler Hat was their third. You can hear much of it on YouTube, and there are streaming options as well as lots of CDs and LPs at Discogs.
The band sported an unusual line-up of guitar, bass, drums, flute and violin. And they still sound like a rock band, and one of the more unique ones you're likely to hear. They cited both the Beatles and Frank Zappa as influences, as well as Syd Barrett, Beach Boys and the Marx Brothers. And it all gets into the mix.
I think you'll find them to sound quite like nothing you've ever heard, and mostly in a good way.