Hey Gav
I'm chasing the same problem, a misfire has cost me an mot fail today and I've identified the fault being no or a very very weak spark at plug 1 (used some natty little lead testers from Halfrauds for 8 squid)
What's puzzling me is that the same coil powers cyl 6 and that's as fit as a butchers.
I've swapped leads to check and it's fine, as is the tester on another cyl.
is this possible??
cheers