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Boris Johnson has admitted he would need EU co-operation to avoid a hard Irish border or crippling tariffs on trade in the event of no deal.
In an exclusive interview with the BBC, the favourite to be next prime minister said: “It’s not just up to us.”
But he said he did “not believe for a moment” the UK would leave without a deal, although he was willing to do so.
Asked about a row he had with his partner, he said it was “simply unfair” to involve “loved ones” in the debate.
Reports of the argument with his girlfriend, Carrie Symonds, on Friday dominated headlines over the weekend after the police were called to their address in London.