British politics is on Monday braced for another pivotal day in the Brexit saga as an increasingly embattled Boris Johnson kicked off proceedings by meeting his Irish counterpart in Dublin, where he offered assurances over the future of the shared border and said a no-deal Brexit would be a "failure of statecraft."

Taoiseach Leo Varadkar made it clear that his government would not allow for the so-called Irish backstop to be replaced with "a promise."