The food is so good at this royal festive dinner that Her Majesty assumes it must be from Marks & Spencer or Waitrose - but then Kate reveals the truth with a double pat on her back pocket.
And there's a late arrival, when Prince Harry's new girlfriend Meghan Markle turns up at the front door.
The film was created for the supermarket by comedy production and content agency Hoot.
The Royal Family were also given the parody treatment in a Mother's Day campaign by the Body Shop.
