73. Contract must be made in writing.

A contract made on or after 27 September 1989 for the sale or other disposition1 of an interest in land2 can only be made in writing and only by incorporating all the terms which the parties have expressly agreed in one document (or, where contracts are exchanged, in each document)3. The terms may be incorporated in a document either by being set out in it, or by reference to some other document4; and the document incorporating the terms or, where contracts are exchanged, one of the documents incorporating them (but not necessarily the same one) must be signed by