Well, to the interested few. I went out to have a look at it today. Ordered a set of jet cleaners and expected to have to do a strip. I had also purchased a tin of carb cleaner and sprayed some into the intakes whilst turning the bike over. One last look over things before pulling the carbs off and I noticed the petrol pipe was kinked down at the fuel pump. I pulled it out its run and re-routed it straight up the outside of the bike, ensuring no kinks and turned it over.......Yipee, off it went and ran sweet as a nut. Thinking back, there had been a small leak from the hose at the carb end so I had cut about 1" off the perished end. Obviously this had caused the hose to kink at the bottom when I stretched it back over the carb. When I was removing the hose to check if fuel was getting pumped through, it was obviously relieving the kink, but slipping it back on blocked it again. So a happy bunny here with an easy fix. Now to get it booked in for its MOT.