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Mujtaba Rahman – managing director at something called the Eurasia Group, a political risk consultancy – is often to be found on Twitter explaining how doomed Brexit is.

The former Treasury and EU Commission analyst today made a pretty extraordinary claim about Lord Frost, the government’s Brexit (re)negotiator.

Rahman said that on a trip to Paris Frost told people in meetings Britain is “waging a political and cultural war”. Frost was in the French capital for crucial talks last week over the French fishing row.

Rahman claimed Frost said “ignore Whitehall” on the basis that the civil service and UK embassies have no solutions “because they’re part of an old regime”.

In a rare intervention, Lord Frost – the minister responsible for implementing the Brexit agreement, who also helped negotiate it – replied to Rahman, denying the story in blunt terms:

“I want to make emphatically clear that it is wholly inaccurate & untrue in every respect,” he said.