I think Xraydice and Big Tudor have the right of it and if you are serious, the only wokka that's going to shift a seriously stuck Disco is a Chinook. You have no idea how much mud can suck.
Google the Surrey Land Rover club or the Kent Off Road Club. They would probably use it as a winching exercise, without the risk of a very expensive
faux pas. 
You will usually find the Land Rover fraternity to be helpful, friendly and possessed of a sense of humour.
PM me if you want me to post the problem on the LRUK forum.
Roger.