Nigel Farage and Brexit Party chairman Richard Tice both called for Sir Kim Darroch to be sacked

The chairman of Nigel Farage’s Brexit Party was last night embroiled in the “Trump files” leak scandal as it emerged that he is in a relationship with the writer whose story brought down Britain’s ambassador to Washington.

Richard Tice, a Brexit Party MEP, is dating Isabel Oakeshott, who last week published leaked diplomatic cables in which Sir Kim Darroch branded Donald Trump “clumsy and inept”, forcing Darroch’s resignation when the president announced he would not work with him.

Security sources said a suspect had been identified for the leaks amid “panic” in Whitehall that a “pro-Brexit Kim Philby” figure has been trying to undermine officials not deemed supportive enough of leaving the EU. Scotland Yard and the intelligence services believe a civil servant with access