Sorry Stu I cant view as I don't have a Google account.

How long was it parked up?

If it would not turn without removing the plug it could have become hydrolocked by fuel, if the float is not seating properly.

When you kick it over with no plug are there any signs of fuel coming up into the cylinder? If there is do not try and start otherwise it will probably lock and bend the con rod.

If not hydrolocked it must have had a partial seizure, so you probably need to at least pop the head off and take a look. By taking the head off you could also check for excess fuel by kicking it over.

Just a few thoughts.