Donald Trump’s former campaign advisers have revealed their anger at how a Cambridge University professor turned FBI informant secretly monitored them before the 2016 election.

Sam Clovis, George Papadopoulos and Carter Page all told the Telegraph how they agreed to meet Stefan Halper, who taught political science, during the campaign thinking he was just an academic.

However it has since emerged that Prof Halper arranged the chats on behalf of the FBI to investigate whether the Trump campaign was helping Russia meddle in the election.

He was secretly recording the conversations, with FBI agents later pouring over the transcripts for signs of a criminal conspiracy between the campaign and the Kremlin.