that property is held on constructive trust by the seller for the benefit of the buyer. This applies to both personal and real property, with additional rules for the transfer of real property (land). Section 2 of the Law of Property (Miscellaneous Provisions) Act 1989 provides that the contract must be in writing, which is not a requirement for the transfer of personal property. Other Constructive trusts also arise with mutual wills; wills created by two or more people at the same time, with the intention that the wills are completely binding. Normal wills can be altered or revoked; when one signatory to a mutual will dies, the will irrevocably binds the other signatories. This is dependent on several things. Firstly, there must be evidence of a contract between the signatories demonstrating that each would make a will in a certain form, and neither would revoke it, as in Walters v Olins. Secondly, the will must make it clear that it is to apply to the other party after death. Until a death occurs, the arrangement is simply a contract and has no effect in equity. Secret trusts are sometimes considered constructive trusts. They do not follow the Wills Act 1837; a requirement for express trusts. The argument is that it is such trusts are intended to prevent fraud by statute. Under this rule, secret trusts would be constructive trusts; the reason they do not have to follow the Wills Act is because they are created by the courts. This is a difficult argument with which to justify half-secret trusts, because since the will mentions the trust, fraud is not directly possible. A more modern argument is that secret trusts are independent and operate outside the will. The trust was created by the donor and trustee during the donor's life, and simply not constituted until his death; it does not have to follow the Wills Act, because it was not created by a will. This view was expressed by Megarry VC in Re Snowden, where he said "The whole basis of secret trusts...is that they operate outside the will, changing nothing that is written in it, and allowing it to operate according to its tenor, but then fastening a trust on to the property in the hands of the recipient". This suggests that secret trusts are not constructive trusts but rather express trusts. Constructive trustees When non-trustees interfere with the