MI5 must investigate ‘security risk’ Boris Johnson after Partygate leaks, David Blunkett says

Call comes after allegation that prime minister left top-secret documents lying around when visitors came to his flat

MI5 should investigate Boris Johnson as “a security risk” following the leaks of TV footage and emails about the No 10 parties, David Blunkett says.

The emergence of the evidence suggests the prime minister’s staff do not have “the first idea about the potential of cyber-attack”, the former Labour cabinet minister warned.

“The counterterrorism division of the Met, together with MI5, should take a very urgent look. I would be very surprised if they’re not,” Lord Blunkett said.

The call comes amid an allegation that Mr Johnson left top-secret documents lying around when visitors came to his Downing Street flat – prompting his aides to ban him from taking the files upstairs.

Martin Reynolds, the prime minister’s private secretary, insisted he approve secret intelligence requests in his No 10 office, after complaints about security in the home he shares with his wife Carrie, The Sunday Times reported.

Dominic Cummings became alarmed over the “frat house” atmosphere in the flat and in the couple’s private rooms at Chequers, the prime minister’s country retreat, the paper claimed.

Lord Blunkett seized on the evidence of parties that has come to light, ahead of the release of Sue Gray’s – heavily censored – report, as early as Monday.

“There’s a real problem, I think, at Downing Street in terms of understanding the genuine security that they should have in place,” he told LBC Radio.

Asked if he considers Mr Johnson “a security risk”, Lord Blunkett replied: “I think so, yes.

“The way that this has emerged – and it’s in the public interest that it has – but the way it’s emerged asks me to ask the question, ‘what if it was a foreign power with malign interests that had actually infiltrated the systems at Downing Street, including CCTV and the like?’.

“It clearly wasn’t, but at one stage, I was thinking, ‘who knows, who’s behind this, as well as Dominic Cummings’.

Lord Blunkett added: “Whilst we must clear up, who did what and why – and whether they let us down very badly, in terms of the breach of rules that they were making – in the long term, we’ve got to get these other issues sorted.”

Theresa May reportedly ordered some intelligence to be withheld from Mr Johnson when he was her foreign secretary, after he earned a reputation for lax security.

Documents are taken home in red boxes by ministers to read overnight, including some at the highly classified “strap” level.

The Sunday Times reported that Mr Cummings found Carrie Johnson and her friends relaxing while the prime minister’s red box sat open and “strap” documents were left lying around.

It also claimed that Ms Gray uncovered evidence that “several” of Ms Johnson’s friends were given the access code to go in and out of the Downing Street flat.