I see. U didnt say. Well I think what normaly happens is they put a charge on the property and he gets the money when you sell it. He will get a percentage of its market value at the time of sale. A charge is something that gets registered with the land registry. This has to be done with a court order and will require some conveyancing.
Pity there is not a "total bastard" charge on a divorce petition huh?

Chris.