Guess what.
MrsMattsv has had a slow(ish) puncture for a few days.
She took it to get it repaired today, to be told that the rim is damaged - was on the inside of the rim so we could not see it. I tried to get the wheel off yesterday to have a look but the f&*^ing nuts had been torqued to about 15bn Nm.
She did smack a big pot hole the other week, so looks like that knackered it, although not as bad as yours Quiff.
Luckily I have found a place locally that can repair it for "about £30". Not sure exactly where she did it so no point going to the council...