MI5 chief warns against overstating Russian interference in Brexit vote
MI5 chief Sir Ken McCallum has acknowledged Russian interference in the 2016 Brexit referendum but cautioned against exaggerating its impact on the final result. His comments follow a political dispute between Prime Minister Andy Burnham and Conservative leaders regarding the legitimacy of the vote.
Why it matters
The debate highlights ongoing tensions regarding foreign influence in democratic processes and the political weaponization of intelligence assessments.
Image source, Getty Images By Becky Morton Political reporter Published 13 October 2026 MI5 chief Sir Ken McCallum has said there was Russian interference in the the Brexit referendum, but warned against overstating its impact on the result.
It comes after Prime Minister Andy Burnham provoked a backlash from some Brexit campaigners by saying it was "clear" there had been interference by Moscow in the 2016 vote.
Sir Ken said it was "a matter of public record" that there was interference in the referendum by online trolls and bots.
However, he suggested Russian trolls would be "delighted" to be front page news again, "despite the comparative unimpressiveness" of their efforts.
He added: "There is a really important difference between interference attempted and outcome swayed.
"I am a little bit anxious that we don't play into our adversaries' hands by making these trolls look 10ft tall."
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