Even the casual observer of trends in estoppel jurisprudence may have noted that discussions of promissory estoppel have recently become less ubiquitous in reported decisions. What may have been less apparent, but of no less significance, is that during this period there has been an upsurge of interest in estoppel by convention as a basis for judicial action. Although this doctrine was once referred to as being ‘as old as the hills’, it had languished in judicial and academic obscurity for many years prior to current interest. More recently it has been hailed as ‘an essential arrow in the quiver of every commercial counsel’. This phenomenon has occurred against the backdrop of a proliferation of so-called ‘equitable’ and proprietary estoppels, and judicial and scholarly exasperation at the disorder into which estoppel issues generally appeared to have fallen.