Peter Phillips, the Queen’s grandson, is seen advertising Jersey Cattle milk in a Mandarin-language advert.
His promotion of the product comes as Harry and Meghan step back from the Royal Family, having declared they don’t want to rely on public funds.
Mr Phillips is shown in a palace being served a bottle of the product by a butler before viewers see a montage of cows grazing on green hills.
Mr Phillips, the son of the Queen’s second child, Princess Anne, and Mark Phillips, is seen gleefully taking a bottle of Jersey Milk from a fridge before looking out at the Shanghai skyline.
“This is what I drink,” he states plainly into the camera, dressed in a suit, clutching a glass of the milk.
While Harry and Meghan have not revealed details of how they will become financially independent, their statement released earlier this month said: “The Duke and Duchess of Sussex take great pride in their work and are committed to continuing their charitable endeavours as well as establishing new ones.
“In addition, they value the ability to earn a professional income, which in the current structure they are prohibited from doing.”
The Duke and Duchess of Sussex will now split their time between the UK and Canada.
While it may be unlikely Prince Harry will be seen advertising Chinese milk, their wish to separate from public funding – which will include their repaying of £2.4 million of taxpayer’s cash spent renovating their cottage in Windsor – means they have been told to step back from royal duties, which includes military appointments.
They will no longer use their HRH titles, Buckingham Palace confirmed at the weekend.