Professor of Equity and Law at Queen Mary, University of London, argues that Browne-Wilkinson's theory is flawed, primarily because if the trust can not be enforced against the trustee's wishes, it is a form of constructive trust. Much of the case law is instead based on Megarry's classification. Resulting trusts work on a principle of "common intention". This is the idea that a resulting trust is a mix of the settlor's intention, and the trustee's knowledge that he is not intended to be the beneficiary. In Carreras Rothmans Ltd v Freeman Mathews Treasure Ltd, Gibson J expressed the principle as: Types Automatic resulting trusts Automatic resulting trusts arise from a "gap" in the equitable title of property. The equitable maxim "equity abhors a vacuum" is followed; it is against principle for a piece of property to have no owner. As such, the courts assign the property to somebody in a resulting trust to avoid this becoming an issue. Automatic resulting trusts occur where an express trust fails. This includes where there is no valid declaration of trust, where there is surplus property, or upon the dissolution of an unincorporated association. Whatever the reason, when a trust fails the property must be passed to someone. This is an application of the equitable maxim that "equity abhors a vacuum". No declaration of trust is the most straightforward form of resulting trust, and is created when a trust is created, but the settlor does not give the form in which the property is to be held. For example, the settlor might give property to the beneficiary to hold for life, but fail to explain what is to happen to the property when the holder dies. When this occurs, the property is held on resulting trust for the settlor, as in Vandervell v IRC. This also occurs where a trust is formed over property which requires formality, but is improperly created (for example, a land transfer that does not adhere to the Law of Property Act 1925). Upon the failure of a charitable trust, the gift may be held on resulting trust for the donor, as in Chichester Diocesan Fund v Simpson, or submitted to variation under the cy-près doctrine. As in Simpson v Simpson, if property is given to somebody who is incapable of acting, it will also be held on resulting trust for the donor. A resulting trust will also be found