Kate, 33, is known to be a fan of the popular drama, previously revealing that she and Prince William watch it together, so she would have no doubt been excited to meet the stars, including Joanne Froggatt, who plays maid Anna Bates, and Laura Carmichael, who plays Edith Crawley, though ever the diplomat, apparently wouldn't be drawn on her favourite characters.

The visit doesn't appear to be mere a perk of being a royal, as aides said she accepted the invitation "to help celebrate what is one of the most successful products of the UK's creative industries, and one of Britain's greatest cultural exports".

Dame Maggie Smith, who plays the Dowager Duchess of Grantham, sadly couldn't attend the meet and greet due to illness.

But the real Duchess was clearly excited to watch a scene from series six being filmed, and enjoyed the tour so much that she reportedly stayed for an extra half-hour.

The Duchess at Downton: Kate Middleton visits the set of Downton Abbey