This section makes a comparatively small change to the existing law. Under Section 25 of the Law of Property Act 1925 a power to postpone sale was implied in every trust for sale unless a contrary intention appeared. Under Section 4 trustees have power to postpone the sale even if the settlor expressly directs them to sell the property immediately. Section 25 itself is repealed by this Act.

Note that this sub-section makes it plain that the Act does not abolish trusts for sale in all circumstances: it simply exchanges a power to sell for a duty to sell. Trustees who should have exercised their duty to sell before the commencement of the Act are not, however, exonerated from their breach of trust -- subsection (3).