Sir Keir Starmer used a Labour donor’s £18 million London penthouse to record a video message urging Britons to work from home during Covid.
In the newly-unearthed clip from December 2021, Sir Keir attacked Boris Johnson’s government for its response to the pandemic.
He also urged people to work from home and get booster jabs to protect the NHS amid the spread of the Omicron variant.
Labour sources have insisted no rules were broken.
Footage shows Sir Keir in front of a picture of his wife Victoria and their two children and an assortment of Christmas cards.
Critics have accused the then-Labour leader of creating the impression, especially given the “sticking to the rules” message being delivered, that the video was shot at the Starmer family home in Kentish Town.
But on Wednesday night it was reported that filming took place at former TV mogul and fashion boss Lord Alli’s luxury home in the Covent Garden.
Sir Keir had to defend use of the accommodation for his son to study for his GCSEs during the general election campaign.
The donation was declared in the MPs’ register of member’s financial interests and listed as being worth £20,437.28.
He told Sky News that he was not going to “let my son fail or not do well” in his exams while journalists were outside the family’s £2m townhouse in north London.
Speaking to the broadcaster from New York City, where he is attending the UN General Assembly, Sir Keir said that the election had been called “not when we expected it”.
“My son happened to be in the middle of his GCSEs,” he added.
“That means there are a lot of journalists outside the front door and in the street.”
He said he is “not complaining”, but “if you’re 13, as my girl is, if you’re 16 as my boy is, that’s quite hard to navigate when you’re concentrating on GCSEs,” he said.
Sir Keir explained: “I said, ‘we’re going to get you out of here and get you somewhere where you can just study and get to school and back without having to go through all of that’.
“And that’s when someone says, well, in which case I can make this flat available to you.
“It’s safe, secure, he can get on.”
The Prime Minister later went on: “I do think sometimes it’s important just to look behind the number and say, ‘what was the human story behind’”.
“I wasn’t going to let my son fail or not do well in his GCSEs because of journalists outside,” he added.
Lord Alli's home has three en suite bedrooms, as well as a kitchen, games room and two dressing rooms.
Tory leadership contender Robert Jenrick told the Daily Mail: “After years of Starmer’s piety, it looks like Mr Rules was trying to hoodwink the country all along.
“He would have been the first to call for this to be investigated if the shoe was on the other foot – it’s only right that equal scrutiny applies.”
Conservative MP Dr Kieran Mullan added: “Starmer says he is ‘Mr honesty and integrity’. If that was not his home, then he has apparently lied to the public.
“Whether you say ‘this is my home’ or put up pictures to that effect, it’s a lie. It’s a visual lie.”
The row over declarations by MPs and senior ministers had threatened to overshadow Labour’s conference, with criticism aimed at both the PM and his ministers for accepting luxury gifts from wealthy donors while announcing cuts to the winter fuel allowance.
Sir Keir has said ministers will no longer take donations for clothing now they are in Government, but left the door open to receiving more access to events, such as the £4,000 worth of tickets to a Taylor Swift concert he accepted from the Premier League.
