The potentially career-ending video of Keir Starmer drinking a beer in Durham was filmed by Ivo Delingpole, the student son of the Breitbart writer James Delingpole.

Delingpole, who graduated from the University of Durham last year, was at his student house in the city, close to a venue where the Labour leader held a political campaign event on 30 April 2021.

According to individuals with knowledge of the video’s creation, it was Delingpole who spotted the Labour leader through the window of Durham Miners Hall. Starmer was drinking with a team of campaigners eating a takeaway curry at a time when the country was still under partial lockdown and large indoor social gatherings were banned.

The short video was subsequently passed to the anti-lockdown activist Laurence Fox, who tweeted it out to his followers.

Mainstream media outlets largely ignored the footage for nine months, but as public fury over parties in Downing Street escalated over the winter, the Daily Mail put the Starmer video on its front page in January and accused the Labour leader of hypocrisy.

The newspaper, along with the Sun and the Telegraph, has since led a concerted campaign to investigate the circumstances surrounding the video, resulting in an announcement from Durham police that the force would launch an investigation into whether Starmer and his fellow campaigners broke lockdown rules.

Ivo Delingpole could not be reached for comment, but his father confirmed that he was the individual who filmed the footage. Ivo has insisted in anonymous interviews with the student newspaper Palatinate that he did not want the footage to be used to excuse Boris Johnson’s rule-breaking and that his decision to film had not been politically motivated.

James Delingpole was an Oxford University contemporary of Johnson’s in the 1980s. He has written for the rightwing Breitbart and other outlets such as the Spectator and the Telegraph. He hosted a live edition of his podcast last month featuring a number of anti-lockdown activists, including Fox.

When the video of Starmer first circulated last April, he tweeted about it without mentioning that his son had filmed it. “Literally no one would care whether or not Keir Starmer broke mask/social distancing regulations if it weren’t for the fact that he has pushed for them even more assiduously than the government. It’s about grotesque double standards. How is this point not obvious?” he wrote.

Starmer said on Monday that he would resign as Labour leader if Durham police fined him over the incident, insisting that he had acted within the law.