The Queen has installed "panic rooms" at Buckingham Palace and Windsor Castle to protect herself and her family from any possible terrorist attack.
It was decided to install the new facilities after the security review at St James's Palace which followed the September 11 attacks. The rooms, which are fortified with 18-inch thick solid-steel walls, are equipped with washing facilities, beds, communications and enough food to last for a week.
Designed to stand up to any possible threat, the bullet-proof chambers are capable of resisting poison gas, mortars or even an anti-tank missile. A third room, similar in design, is to be built at the Queen Mother's former residence Clarence House, in anticipation of Prince Charles's move there later this year.
The new facilities replace the safe rooms which were originally designed to shelter the royals from bombing raids. It was judged that these smaller "last-resort" rooms were not adequate to stand up to the threats of modern terrorism.
The two shelters, estimated to have cost £600,000 each, are said to be concealed behind wood panels. Security experts have warned that in the event they are put into action, the Queen would have to take her beloved Corgis in with her to prevent them from giving the location away.