This chapter launches a concise but sustained critique of the historical ultra vires debate and the main positions in it – especially the so-called modified ultra vires theories, which it argues should be renamed so that ultra vires can be reappropriated for the inherent common law jurisdiction to supervise the bounds of official powers. The ultra vires debate started in the context of a review of non-statutory power, but the debate quickly moved on to become one about the radical English doctrine of parliamentary sovereignty. A high degree of consensus on that doctrine and a rather surreal choice of premises by the ‘common law’ and ‘legislative intent’ camps, respectively, led to an intense but ultimately frustrating debate. The framework presented in earlier chapters offers a way to circumvent the terms of the historical debate and take a fresh look at the vitally important questions at its heart.