Britain's Queen Elizabeth II was to tell her "brave country" to stand firm as it faced up to a nuclear war, in a previously secret speech prepared for her in 1983.

With Britain on the brink of annihilation at the hands of a nuclear-armed Soviet Union, the queen was to say that the dangers were "greater by far than at any time in our long history", according to the document released from archives on Thursday.

She would also have appealed to the British people to remember the qualities which saw them keep freedom alive in two previous world wars.

"As we strive together to fight off the new evil let us pray for our country and men of goodwill wherever they may be," the text declares. "May God bless you all."

Fortunately, the queen never had to give the speech and it is believed she has never even seen the text.

It was drafted by government officials at the height of the Cold War as part of a wargaming exercise designed to work through potential action if nuclear conflict became a reality.

Details of the WINTEX-CIMEX 83 exercise were among the latest tranche of government documents to be released by the National Archives.

Although only a simulation, the text of the address -- supposedly broadcast at noon on Friday March 4, 1983 -- evokes the fears of the time as the monarch seeks to prepare the country for the unimaginable ordeal ahead.

There are references to her "beloved son Andrew", who was then serving as a Royal Navy helicopter pilot, and the address by her father George VI on the outbreak of World War II -- a speech later dramatised in the film "The King's Speech".

"Now this madness of war is once more spreading through the world and our brave country must again prepare itself to survive against great odds," it reads.

"I have never forgotten the sorrow and the pride I felt as my sister and I huddled around the nursery wireless set listening to my father's inspiring words on that fateful day in 1939. Not for a single moment did I imagine that this solemn and awful duty would one day fall to me.

"But whatever terrors lie in wait for us all the qualities that have helped to keep our freedom intact twice already during this sad century will once more be our strength."

In the exercise, the Orange bloc forces -- representing the Soviet Union and its Warsaw Pact allies -- launch an attack on Britain with chemical weapons.

The Blue forces, representing NATO, retaliate with a "limited yield" nuclear strike forcing Orange to sue for peace.

The civil servants taking part even drew up mock newspaper front pages, the declassified documents reveal. The imaginary version of The Sun tabloid had a blank front page and waited until page two to declare "War -- the word we didn't want to print".