The first affair Princess Anne participated in was allegedly with her then-bodyguard, Sergeant Peter Cross in 1979, six years after marrying Mark. Peter was a member of the Royal Protection Squad and had been assigned as Princess Anne’s personal bodyguard. Reportedly, he was only on her services for about a year before the affair was discovered.
In The Crown, the moment that Princess Anne’s affair becomes public knowledge is when Queen Elizabeth tells her daughter that Peter will be reassigned.
She threatens to move Peter back to desk work, making it clear she knows of the pair’s scandalous affair. In the show, Princess Anne responds by pleading with her mother, “He’s the only thing that makes me happy.”
Allegedly, after their affair ends, he sells the story of it to tabloids, revealing that she had a codename for her secret lover, “Mrs. Wallis,” which she would use when calling him on the phone to keep her identity a secret.