This article attempts to investigate an aspect of the English law on limitation of actions which has received little academic attention—its application to restitutionary claims. It will be suggested that, as the essence of a plaintiff's claim is the injustice of the defendant retaining a benefit gained at his expense, the running of time should be a defence to a restitutionary action where its passing has sufficiently eroded the injustice of that retention. In theory this should be a matter for decision purely on the facts of each case, but additionally the societal need to discourage stale litigation often requires an overall time bar based on the Limitation Act 1980. This perspective suggests a number of particular conclusions which are summarised at the end of the discussion.