The 42-year-old son of Princess Anne is seen holding a glass of milk in front of a stately home, with the caption: ‘British Royal Family member Peter Phillips.’
Mr Phillips, who grew up on his mother’s estate in Gloucestershire, boasts in the advert of being brought up on Jersey milk from the herd at Windsor.
A spokesman for Longleat House, the Wiltshire property used in the commercial, said permission had not been granted.
The revelation will intensify the row about ‘royals for rent’, as the Duke and Duchess of Sussex embark on their new lives.
Harry and Meghan have had to promise not to use their HRH titles to cash in as they set about becoming ‘financially independent’.
Mr Phillips and his sister Zara have never had HRH status, and both have come under scrutiny in the past for the way they make money.’
Read more: ‘Royal Peter’ for hire in China: As Prince Harry flies to Canada to earn millions, the Queen’s eldest grandson Peter Phillips is revealed to be trading on his royal status by advertising milk on TV