Was at the boat Saturday puttering about - hey it was up to 6C inside!
Hand cranked the engine again, which I did about every 3 weeks over the winter and this time had with me a smaller size pipe wrench to try and see if I could not persuade the stuck distributor to turn.
Backed off the clamp and in trying to get the pipe wrench to fit the blasted thing turned!
Put my hand on top and could easily turn it left or right; very carefully I put it back to its original position. I am guessing that 5 months of winter with a splash of penetrating fluid was all it needed. Phew!
Another month and it'll be warm enough to start 'er up!