BUCKINGHAM Palace boasts 775 rooms - so it's lucky the Queen's got a handy way of getting around them all quickly.
The 93-year-old monarch has a secret passageway hidden behind a mirror that helps her take a short-cut from her private apartments to the state rooms.
The presenter told the camera: "This is the White Drawing Room. Looks beautiful, doesn't it?"
Gesturing at an ostentatious mirror and ornaments, she continued: "Beautiful cabinet here, wonderful vase, gold candlesticks there. Absolutely lovely."
The star then began to pull the mirror and its components away from the wall, adding: "But if I just rather gently pull on this you will see...I tell you it takes a bit of muscle, the Queen must have more muscles than you realise.
"If you pull this open you can see that actually behind this there is a secret passage leading to the Queen's private apartments."
The camera then panned around to Anna Reynolds, curator of the Royal Collection True, who was asked by Kate about the purpose of the hidden door.
She explained: "This is the way to the Queen's apartments.
"Often when the Queen is meeting guests, they're lined up for her here in the Music Room for her to meet.
"It allows her to make an entrance without having to walk through all of the different palace rooms."
According to The Royal Family's website, the London-based palace houses 19 state rooms, 52 royal and guest bedrooms, 188 staff bedrooms, 92 offices and 78 bathrooms.
It comes as it was revealed the Queen has a secret escape tunnel out of Windsor Castle.
According to a BBC documentary, there is a trapdoor hidden beneath a carpet.
In other royal news, we told you the five times Meghan Markle upstaged Kate Middleton.
We also revealed that Prince Harry felt "constrained" and wants Archie to "grow up away from pomp and royalty".