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"Even if the rest of the house is destroyed, it will drop intact to the ground floor"

From the outside, Highgrove House may look like a quintessentially English Georgian country house. But a royal author has revealed that it's had a thoroughly modern upgrade to keep its VIP residents safe.

Prince Charles and Camilla, Duchess of Cornwall reside at Highgrove, near Tetbury in Gloucestershire. The nine-bedroom, six-bathroom mansion is renowned for its beautiful gardens, which featured in the BBC's documentary celebrating the Prince of Wales' 70th birthday last November, along with a Gardener's World special.

Now, a royal biographer says security has been increased at Highgrove, with the addition of a steel-lined room. The feature, Brian Hoey claims, is to keep the heir-to-the-throne and his wife safe during a terrorist attack.

In his book, Not in Front of the Corgis, Hoey explains the so-called 'iron room' is on the first floor. It measures 20ft by 20ft, and "has been so built that even if the rest of the house is destroyed, it will drop intact to the ground floor".

"Inside are medical supplies," he writes. "Including containers of Charles and Camilla’s blood group, long-lasting food and drinks, an armoury, radio transmitters equipped to obtain a signal even within its steel walls, air purifiers and chemical lavatories."

Hoey also claims the Duke and Duchess of Cornwall would be able to survive for weeks living inside the room.

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