If Boris Johnson was elected on a single slogan, it was ‘Get Brexit done’. He then claimed it was done at the end of 2019 in the terms for leaving the EU he agreed. Not so. Today legislation will be introduced by the Foreign Secretary Liz Truss to unilaterally overhaul a central pillar of the UK’s negotiated exit from the EU, the Northern Ireland Protocol – which is seen by the EU, whatever the government may claim, as a breach of the UK’s international treaty obligations.