Dear Serena,
Thanks for your replies. I didn't know about graves in the churches you mentioned, but then I've never been to Leighton Buzzard! If you would be so kind to take any details you think might be relevant, that would be fantastic.
You are right that William Cotching, whom you mention, was one of Kisby's 14 or more children, I'd already found his record.
Kisby died in 1925, aged 90, a pretty good age for someone of his lifestyle! I don't know when his wife died. His death was registered in Leighton Buzzard district, but I can't be more specific than that.
Another contact of mine had found that jail record; also imprisoned at the same time was John Baines, his brother in law (Ann's brother).
It turned out that Cotchings was actually Kisby's mother's maiden name; I personally don't believe he would have been that bothered by going to jail to change his name, though. I suspect he might not have got on with his father. At least of his brothers also changed surname to Smith, for no apparent reason!
There's certainly a lot of detail about this colourful family that we'll never find out!
Regards, Darren