Curiosity only!!!
If a house is in joint names and both parties have contributed to the payment of the property with a joint mortgage what happens if one of the party wants to get out!!! For example a couple whose partnership/marriage has broken down and one party wishes to get their share out of the propery. Can one party legally make the other party either buy them out or force a sale?
Not since the Trusts of Land and Trustees Act 1996 (not sure about the year). Before, it was true that one party could force a sale on the other; now, that is no longer so, and if the parties cannot come to an agreement as to what to do, the last resort is to get a court order. In the case of divorcing spouses it will be family law rather than land law that applies (afraid I know nothing of family law though).
I think the answer by vittoria is incorrect as I don't think the 1996 Trusts of Land and Appointment of Trustees Act made any significant difference. Any of the joint owners can generally force a sale, though the sale may be subject to the rights of people in residence.