"Snell's Equity" includes them in its section on express trusts, as does "Underhill and Hayton", although both opine that they are better classified as express trust with constructive elements.53(1)(b) of the Law of Property Act 1925 requires that "a declaration of trust respecting any land or any interest therein must be manifested and proved by some writing signed by some person who is able to declare such trust or by his will".