Thank you all so much for your advice and for taking the time to do searches. There's a lot to think about.
Checking the witnesses on the marriage certificates was a good idea that hadn't occurred to me, but weren't any help. None of the names linked up. I spent some time today tracking the women witnesses down to see if perhaps they were sisters with married names, but no.
And then I came across an Alfred Edwin Horton, born in Devon in 1842 (my Alfred had the Torquay marriage). His father Joseph was a musician (born in Warwickshire) as was the eldest son Joseph, and in the 1840 census, Joseph's father was living with them in East Stonehouse, Devon, and was called Thomas! Now, it's a big "What If?", but what if this Joseph is my Alfred's uncle, his father Thomas being brother to Joseph? The Warwickshire connection might link to the Ann Brown/Horton/Boddington that John and Heywood found.
My brain hurts. I'm going to sleep on all this and tomorrow have a look at what you've found, then start trying to make sense of it all. Thanks once again to everyone for your time, help and suggestions.
