According to the documentary Inside Sandringham: Holidaying with the Queen, the Queen has a special (and very unique test) that any staff member who works with the family at Sandringham during the holidays must pass. In the doc, royal recruitment expert, Tracey Waterman, explains how she hand picks the best of the best for the Christmas staff.
“The difference between housekeeper in a five-star hotel and in a royal Palace would be attention to detail," Waterman says. "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."
Waterman says she will guide the candidate to the area where she's hidden the dead fly to make sure they have a real chance to spot it. If they do, the next test is how they handle the situation.
“At this point I’d expect them to see the dead fly, and hopefully pick it up, " she says. "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!"