Boris Johnson hosted the Tory peer who funded a lavish refurbishment of his Downing Street flat for dinner the day after the second national coronavirus lockdown came into force in an apparent breach of the rules, leaked files suggest.

David Brownlow, who provided £58,000 to cover some of the cost of the renovations, which included £2,260 worth of “gold” wallpaper, joined the then prime minister in the small dining room at No 10 on Friday 6 November 2020.

Just 24 hours earlier, tough lockdown restrictions banning people from any social meetings indoors, had been introduced to help control the spread of the virus. “Unless we act, we could see deaths in this country running at several thousand a day,” Johnson had warned.

In WhatsApp exchanges later that month, Johnson messaged Lord Brownlow to complain that parts of his No 11 flat looked a “bit of a tip”, asking him for “approvals” so that his interior decorator Lulu Lytle could “get on with it”.

His then ethics adviser, Christopher Geidt, later found that Johnson had not broken the ministerial code over the payments for the Downing Street flat refurbishment but criticised him for acting “unwisely”.

Johnson’s apparent meeting with Brownlow after lockdown restrictions were imposed is one of several potential further lockdown breaches by the former prime minister revealed in leaked files seen by the Guardian. They raise further questions about Johnson’s integrity during his turbulent three years in office.

A log of Johnson’s meeting with Brownlow is contained in a cache of files from his private office seen by the Guardian. The leak was obtained by Distributed Denial of Secrets, a US non-profit that archives data leaks.

Johnson quit as prime minister in July 2022 as Tory MPs turned on him after a series of self-inflicted scandals including the Partygate affair, which resulted in him being fined by the Metropolitan police for breaking lockdown rules.

He then stood down as a Conservative MP in June 2023 after an investigation into the Partygate scandal found he had misled parliament and recommended a lengthy suspension from the House of Commons.

In a further potential breach, the files also suggest that on Saturday 20 June 2020, the day after the surprise birthday party in the cabinet room that led to his police fine, Johnson and his then fiancee, Carrie Symonds, now his wife, hosted three guests for a “private appointment” at Downing Street.

A close friend of Carrie’s who specialises in “vibrational” music treatments; the friend’s mother, a fellow natural medicine practitioner; and the journalist Alex Wickham were welcomed in the “flat/garden”, according to a record of the prime minister’s activities that day.

Social gatherings indoors were still forbidden in June 2020. At the time, Johnson’s Downing Street denied reports he had celebrated his birthday with family friends in the flat on the evening of 19 June, claiming he had hosted them outside.

A log of Johnson’s activities the following day, however, indicates the rules may have been broken then. In addition, an entry for 19 June suggests he and Carrie paid a visit to one of her family members who lived in south-west London.

The previous week, Johnson had asked the public during a Downing Street press conference to “continue to show restraint and respect the rules which are designed to keep us all safe”.

In another possible breach, a heavily pregnant Carrie hosted her close friend Nimco Ali overnight at Chequers, the prime minister’s official country house, on the same day that Johnson announced the first lockdown in March 2020.

“From this evening I must give the British people a very simple instruction – you must stay at home,” he said in his national address on 23 March. “Because the critical thing we must do is stop the disease spreading between households … You should not be meeting friends. If your friends ask you to meet, you should say no.”

The leaked files also appear to confirm reports that Johnson hosted a baby shower for his fiancee at Chequers at the start of the pandemic, despite having warned two days earlier that many families would lose loved ones in the “worst public health crisis for a generation”.

Carrie invited more than a dozen close friends, including three Conservative government aides, to Chequers in Buckinghamshire for the lunch and afternoon tea party on Saturday 14 March 2020, six weeks before the birth of their son.

Just two days later, Johnson told the public that they should stop non-essential contact with other people and all unnecessary travel. Pregnant women were among those he said should be particularly careful.

When reports of the baby shower first emerged in June that year, Downing Street refused to comment. But a file in the leaked data logging his activities appears to confirm for the first time that the gathering did take place.

The confirmation will rekindle speculation that Johnson may have delayed announcing the more stringent advice by several days to avoid having to cancel the baby shower.

Wickham, Ali, and Brownlow did not respond to requests for comment.

Johnson and his wife did not respond to multiple requests for comment. After publication, Johnson emailed a statement to the Guardian that did not respond directly to questions relating to potential further lockdown breaches.

The statement denied that his private office misused a subsidy scheme intended to support an ex-PM’s public duties. The public duty costs allowance (PDCA) should not be used for private or commercial purposes.

“This story is rubbish,” he said. “The PDCA has been used entirely in accordance with the rules. The Guardian should change its name to Pravda.”