Mark Harrison declined to reveal what he captured, but said it would 'embarrass Prince Andrew and the Royal Family' if it were released.
It is understood the Duke insisted the picture never become public, but Mr Harrison hinted that it may feature in a forthcoming film about how the BBC secured the interview. As a dramatisation, producers may feel free to recreate their own version of the 'jaw-dropping' image.
A source close to the Newsnight interview who has seen the original photograph said that if it became public 'it will be so shocking, especially if it is decontextualised.
Mark Harrison declined to reveal what he captured, but said it would 'embarrass Prince Andrew and the Royal Family' if it were released
Prince Andrew takes an early morning ride accompanied by a groom in Windsor on Saturday
'Our jaws dropped to the floor when we saw it. It would cause Andrew much embarrassment – and imagine how high the bar has to be to cause him embarrassment after everything that has happened.'
The Duke effectively became a pariah following his catastrophic interview with Emily Maitlis about his relationship with paedophile financier Jeffrey Epstein and claims – which he has always vehemently denied – that he had sex on three occasions with sex-trafficking victim Virginia Roberts.
Mr Harrison, an award-winning portrait photographer, said of his shot: 'It has been seen by only a few people but it would be a big deal for the Royal Family. There is a lot more from that day that is not yet in the public domain.'
The source added: 'It's the kind of thing which would make the public drop their cornflakes. It is definitely not what Andrew would want out there and apparently he insisted that it remained secret. It was not one of the shots the BBC released.
'There is, of course, a chance that it will at some point come out for all to see, perhaps if the price is right. Of course the movie about the interview is happening so that is a possibility.'
A source close to the Newsnight interview who has seen the original photograph said that if it became public 'it will be so shocking, especially if it is decontextualised
Prince Andrew was spotted driving his car in Windsor on Saturday afternoon
Filming starts on Scoop in November based on a new non-fiction book by former Newsnight producer Sam McAlister about how the BBC secured some of its landmark interviews, including the bombshell encounter with Andrew at Buckingham Palace on November 14, 2019.
In February, Andrew settled a sexual assault case Ms Roberts filed in the US under her married name Giuffre, for an undisclosed sum. Under the deal, the Prince made no admission of guilt.
The Prince's spokeswoman declined to comment on the photograph last night, and the BBC did not respond to a request to do so.