Boris Johnson has been referred to police by the Cabinet Office over claims that he broke lockdown rules by hosting family and friends at Chequers during Covid. The visits to the former prime minister’s grace-and-favour residence were found in his official diary by his government-funded lawyers as they prepared his defence for the public inquiry into the pandemic. They raised the issue with senior officials in the Cabinet Office, who then referred the matter to police as they were obliged to do under the civil service code, and also to the privileges committee, which is investigating whether Johnson lied to the Commons over Partygate. The former prime minister, who quit last July in large part due to the revelations of a string of lockdown-breaking gatherings at Downing Street that became known as the Partygate scandal, has written to the Cabinet Office denying breaking strict lockdown rules. His team called the referral a “clearly politically motivated attempt to manufacture something out of nothing”. However, the development, revealed by the Times, puts further pressure on Johnson, who remains an MP and is fighting for his political career. The Metropolitan and Thames Valley police forces have confirmed they are considering the evidence of potential lockdown breaches between June 2020 and May 2021 at Chequers in Buckinghamshire. Johnson and his wife, Carrie, who is expecting the couple’s third child, and his eighth, repeatedly stayed at the country home during the first lockdown when rules forced people to stay at home and explicitly barred them from mixing with other households. A statement from Johnson’s office said his lawyers had written to police to “explain in detail why the Cabinet Office is entirely wrong in its assertions”. It read: “No contact was made with Mr Johnson before these incorrect allegations were made both to the police and to the privileges committee. This is both bizarre and unacceptable. “For whatever political purpose, it is plain that a last-ditch attempt is being made to lengthen the privileges committee investigation as it was coming to a conclusion and to undermine Mr Johnson. Mr Johnson’s lawyers have tonight written to the police forces involved to explain in detail why the Cabinet Office is entirely wrong in its assertions. “The events in question were all within the rules either because they were held outdoors or came within another lawful exception. They include regular meetings with civil servants and advisers.” Rachel Johnson, the journalist and sister of the former prime minister, said on LBC that “all rules were followed whenever I went to Chequers”, adding: “If [Johnson] has questions to answer, he will definitely be answering them.” The revelations came to light only because Rishi Sunak’s government agreed to foot Johnson’s legal bills for the Covid inquiry, the Guardian was told. Sources said that no minister was involved in the decision to refer Johnson to the police. He handed over his ministerial diaries, which featured details of all his meetings including visitors to Chequers, to the lawyers, who while conducting the “disclosure review” decided they were duty-bound to raise the potential breaches of the rules. These were flagged to senior officials at the Cabinet Office who, in turn, felt obliged under the terms of the civil service code – which states that they must report evidence of criminal or unlawful activity – to refer the matter to police and the privileges committee. A source told the Guardian the documents revealed “fairly clear evidence of criminality” given strict lockdown rules in force at the time. While those at parties in No 10 were government employees, leading Johnson to claim he was following an exemption for gathering for the purposes of work, the same could not be said of all those invited to Chequers, it was claimed. A Cabinet Office spokesperson said: “Information came to light during the process of preparing evidence for submission to the Covid inquiry. It was identified as part of the normal disclosure review of potentially relevant documents being undertaken by the legal team for inquiry witnesses. “In line with obligations in the civil service code, this material has been passed to the relevant authorities and it is now a matter for them.” The privileges committee, which postponed a meeting on Tuesday as a result of the latest revelations, is due to report back next month and, if it recommends suspending Johnson for more than 10 days, he could face a byelection. The cross-party group of MPs, which has a Tory majority and Labour chair, has for a year been looking into suggestions Johnson misled parliament by denying any Covid rules were broken. The revelations are expected to substantially delay proceedings. Johnson will be expected by the committee to deliver fresh written evidence giving an explanation, the Guardian was told. Those with knowledge of the evidence said they expected him to try to defend the gatherings as being meetings outdoors, for work purposes, or for the purposes of care. Lindsay Jackson, spokesperson for the campaign group Covid-19 Bereaved Families for Justice, said: “These revelations make a grim mockery of Boris Johnson’s claims that he didn’t break his own lockdown rules. If he had any respect, he’d quietly step back from public life and reflect on the pain and suffering he has inflicted on so many.” A Thames Valley police spokesperson said: “On Thursday we received a report of potential breaches of the health protection regulations between June 2020 and May 2021 at Chequers, Buckinghamshire. We are currently assessing this information.” The Metropolitan police, whose jurisdiction does not cover Buckinghamshire, said: “We are in receipt of information from the Cabinet Office passed to us on 19 May 2023, which we are currently assessing. It relates to potential breaches of the health protection regulations between June 2020 and May 2021 at Downing Street.”