This commentary critiques the Court of Appeal decision of Southwell v Blackburn that involved a successful proprietary estoppel claim by a former cohabitant. It will argue that although the decision appears in some respects inconsistent with previous authority, it does suggest that proprietary estoppel could have a greater role to play in cohabitation disputes. Nevertheless Southwell is by no means a landmark ruling and nor is proprietary estoppel the panacea for cohabitants as it suffers many of the limitations levelled against the more commonly used common intention constructive trust. If the courts were to prioritise or develop proprietary estoppel further in this context, it would need to modify the traditional requirements of e...