Back. I basically had a big needle stuck into my knee and wangled around (without anaesthetic!) to try to get a blood specimen direct from the area that is giving me trouble. They were checking for infection around my prosthesis (my knee joint and half of the bones are now metal) as it has been hurting me daily for a few weeks now.
As I suspected, it wouldn't appear to be infection (which would have been a very serious complication requiring major surgery), but that leaves the plastic bushes that hold my knee joint tight as the chief suspect.
That is the better of the two scenarios, but if it is the case it will still mean an invasive operation that will leave me out of work for 2 to 3 months. I've already had to have them replaced once, so know what it entails if the bushes are worn out. It's not nice.
Oh well, the joys of having half a metal leg!
Thank you all very much for the good wishes.
StevePSB