On the ITV News website, it is Mr Lee who wrote the news story published on March 15.

After university, Mr Lee went to work as a senior video journalist at Made Television Ltd, where the Channel Manager and later network head of editorial was Chris James. Mr James, a one-time newsreader and reporter, was from December to February working inside Downing Street trying to make sure the Stratton project would run smoothly. Mr James was brought in for his “technical expertise”.

He has posted photographs of himself on his Instagram account proudly at the door of Number 10. Or else posing with Palmerston, the “the gorgeous Treasury Pussy [cat], casually hanging out in a corridor deep inside Number 10”; Mr James adding: “He’s much nicer than Larry [the Downing Street cat]. Cool and calm and sweet. And unlike Larry, he didn’t scratch me.”

Mole could easily be within Downing Street

Suspicions have fallen on Mr James as the possible whistleblower and source of Mr Lee’s exclusive in March, although his present employer said that was a “daft” suggestion. 

Mr James could not be reached for comment. A separate source said that the world of television production was “tight knit” and everybody had connections.  

A source told The Telegraph that the still photographs of the inside of the room passed to ITV News matched exactly “pixel to pixel” images that were found on a server or USB stick of a company involved in advising Downing Street on the press briefings.

However, the source said that while suspicions might have fallen on the technical team working on the project, the wide circulation of videos meant the mole could easily come from within Downing Street.

What’s more, said one source, the leak was to be applauded, with the public interest outweighing any concerns about Downing Street confidentiality.