Slightly unfortunate timing: I would probably be able to answer this question very quickly were I at home with my notes on old British Championships and my chess library available but I'm not.
However, I do have a computer with me and I have been able to find the answer via online newspapers. John H Watts played in the 1960 British Championship in Leicester and scored 3½/11. (Note that the 1960 championship is one of the few which I have yet to digitise for BritBase. It's actually next on my list to do when I get home - you see what I mean by unfortunate timing.)
EDIT: further info - 3½ wasn't the lowest score - CM Malcolm (Glasgow) and M Thompson (Southampton) scored 3/11. Curiously, Watts's name wasn't among the original starters listed in the Times on Monday 15 August but this is not unusual as there were often last-minute changes/additions to the line-up, notably in 1956 when Alexander entered at the last minute and went on to win the title. Elaine Pritchard tried to do the same thing in the Ladies Championship in 1959 but her entry was turned down. BH Wood was scathing about the apparent double standards.
I don't think Watts ever won the WECU title. There is a
list of WECU winners on the Chess Devon website and his name didn't appear on it.