Boris Johnson first British prime minister to be interviewed under police caution, leaked document suggests

• Boris Johnson is one of several people sent a police questionnaire about partygate claims.
• A leaked copy said recipients were asked to provide a response under caution.

Boris Johnson has become the first prime minister to be questioned under caution by police, a leaked document linked to the investigation of "partygate" suggests.

The prime minister is one of several people working at Downing Street to have been sent a questionnaire by London's Metropolitan Police, a spokesperson confirmed to Insider.

The document is part of its investigation into allegations that 12 events may have breached COVID-19 lockdown rules.

Johnson may have attended as many as six of these events, according to widespread media reports. He has admitted being at one, a garden party in May 2020 which he told MPs he "believed implicitly" was a work event.

According to a leaked copy of the generic questionnaire, which was published by ITV News on Tuesday night, recipients are informed at the outset that they have an opportunity to provide "a written statement under caution".

It said respondents "Do not have to say anything but it may harm your defence if you do not mention when questioned something which you later rely on in court."

Those responding were told to "ensure the caution is read and understand prior to any answers to questions being provided".

This level of police questioning would be a historical first for a British prime minister.

Tony Blair was interviewed by police during the cash-for-honours scandal in 2007, however this was never under caution. Blair later said that had he been interviewed under caution he would have felt obliged to resign.

Johnson has repeatedly refused to say whether he would resign if he is handed a fixed-penalty notice for any COVID-19 rule breach.

Although partygate has rocked his leadership, increasingly the consensus among Conservative MPs is that the prime minister may yet survive.

This new chapter in the partygate saga could put the pressure back on.

Angela Rayner, Labour's deputy leader, said: "This is an embarrassment that for the first time in UK history we have a PM interviewed under police caution."