Cheers Andy/AAAC..
There have been a small number of changes recently with a new bike which I set up as usual, however I put the drop in performance down to a recent holiday (plus the possible BKool update), performance has slowly improved to pre October levels however the pain in the muscles (above my knees) at 250 watts plus is staggering. Additionally, I recently changed my pedals from the shimano (Look stylee) to Boardman SPD which I now think are not offering my feet a 'flat' platform and my feet/knees are 'rolling' a little.
Thank you for your help and advice chaps and I'll invest some Christmas time into back to basics set-up..
PS. My thighs are very sore today and that's from a trundle on Middlefart..
Merry Christmas yawl..