After three years and two missed deadlines, we must leave the EU on October 31." Thus did Boris Johnson launch his campaign for leadership of the Conservative party at a pivotal moment in the UK's history. Choices made now will reverberate for generations.

Trusting Johnson's words is always foolhardy. But the implications are clear: if he cannot obtain a better deal than Theresa May's (which the House of Commons has rejected three times), he must either turn tail or choose a no-deal Brexit.

Leaving the EU is in itself damaging: it will worsen the UK's trading opportunities and influence