The rise of Ukip and the highway to Brexit was greatly smoothed by the widespread perception that British governments had lost control of immigration. For many years, we purists in matters of nation-state independence struggled to articulate a stand-alone ‘sovereigntist’ argument that would catch fire with the wider public. But then Tony Blair threw open the UK labour market to millions of workers from the A8 EU accession countries, without even taking advantage of the transitional controls offered to existing member states by Brussels.