360 Rear Main Seal

Ok, big thanks all for the swift responses, I will let you know how we get on.

If we resort to number 2, having to loosen the crank, how would people recommend going about that? (Hopefully not needed!)
I wouldn't worry about loosening the crank until to try the sneaky pete while rotating crank at the same direction. If I have enough help I try to get someone to rotate the crank and also have someone tap on the other end of the seal to give it a boost as you pull on the other end with the sneaky pete!!