The proprietary status of the contractual licence has long been a matter of dispute. In Arnold v Ashbum–Anstult the obiter remarks of Fox LJ signalled a return to orthodoxy in this area of the law. Unless a contractual licence can be supported by facts sufficient to support a constructive trust (and these, too, were restrictively defined by Fox LJ), it will not bind third parties. However, Fox W did not discuss rights over land arising by way of estoppel ( ‘estoppel rights’). The proposition that these can bind third parties has never attracted the controversy that surrounded the proprietary status of contractual licences. Nonetheless, due to the potential overlap between the two types of licence, it is a proposition that needs urgent re-evaluation in the light of Fox W’s views on contractual licences.