The recent article by Keir Starmer, Labour spokesman on Brexit, setting out the Party’s commitment to continued British membership of the EU single market and the customs union for a transitional period post-Brexit is a welcome and significant development in the European debate. In the short term it will give Labour a political and intellectual basis on which to criticize the government’s conduct of the Brexit negotiations, particularly in relation to the form of the transitional period to which the government is now committed. It would be overoptimistic however to claim that the Starmer initiative represents a comprehensive or sustainable approach to Brexit over the longer run. “Constructive ambiguity” stays in place, even if it is now more intelligently constructed.