The Duke and Duchess of Cambridge have a small and loyal team around them to help look after their family and assist with their royal duties.
While their household is far smaller than other members of the family, like the Queen and Prince Charles, they rely heavily on their team for everything to run smoothly.
For many people, working for the royals and getting to call Kensington Palace 'the office' would be the dream - so it's hardly surprising that the family are pretty picky when it comes to who they hire.
And according to a recent job ad, they have one very strict rule that all staff must follow.
In the online application for a housekeeper role, the couple specified that applicants had to be good at "maintaining confidentiality and exercising discretion".
They described the role as an "exciting opportunity" and said it was a "supportive and positive team".
The ad read: "You will be a self-starter who also enjoys working collaboratively.
"You will be keen to take on new challenges as these arise and develop your own knowledge and skills."
Anyone who wants to be a housekeeper for the Queen must pass a secret test before they get the job - so there's a chance she may have passed her idea onto Kate and Wills' staff.
According to Tracey Waterman, the head of recruitment, the team put the secret challenge to all interviewees to see how they react.
She explains that she will place a dead fly on the fireplace or carpet of the room to see if they notice it - and what they do if they spot it.
Speaking during Channel 5's documentary Sandringham: The Royals at Christmas, she said: "The difference between housekeeper in a five-star hotel and in a royal Palace would be attention to detail.
"One of the tests I like to do, to see if a candidate has potential eye for detail, is to place a dead fly, either in the fireplace or on the carpet.
"Once the dead fly is placed, I then bring the candidate into the room.
"I lead them into the room quite slowly, just giving them a chance to glance at the room, have a little look at what we’ve got inside the room.
"Bringing them to the fireplace, maybe highlighting that we’ve got a beautiful fireplace."
"At this point I’d expect them to see the dead fly, and hopefully pick it up."
But it's not just about spotting the fly, it's what they do if they do notice it.
She adds: "It’s a great test, maybe out of 10 people half the candidates will notice the fly. One out of ten will actually bend down and pick it up, that’s the special housekeeper."
