As Millett LJ recently remarked, there can be no doubt that ‘the most difficult question’ to be solved in the law of restitution is the exact circumstances in which a proprietary restitutionary remedy will be available to a restitutionary claimant. The boundary between restitution and property is still largely unmapped and continues to generate controversy. What is needed is a comprehensive and systematic enquiry into the effects that the various restitutionary factors (mistake, duress, failure of consideration and so on) have on the passing of property between plaintiff and defendant. That, however, would require a whole book, or, at the very least, a series of articles. This article takes a modest step in that direction by concentrating on one specific topic within the area of restitution and property, viz, the inter-relationship between the law of restitution and resulting trusts.