Government officials considered deliberately flooding parts of Essex to stop central London from being swamped by flood waters, according to newly-released papers.
It was suggested as gates for the Thames Barrier were stranded by a dock strike in Teesside in the late 1970s.
The idea was to breach flood defences downstream so that some of the water would flood in to low lying land in Essex and Kent, the contingency planning documents dating from July 25, 1979 to December 22, 1983 from the National Archives state.
Such drastic action would have meant "major political difficulty" for the Government, it was stated.
Margaret Thatcher declared it was "even worse than we thought" after learning the details behind the break out at the top security Maze prison in which 38 IRA inmates went on the run.
The then-Prime Minister penned her thoughts across the top of a secret Government document which landed on her desk five days after the mass escape from the Northern Ireland jail on 25 September, 1983, became the worst prison break-out in British history.
In the immediate aftermath, strongly-worded advice sent by telegram from the Foreign Office to its territories stressed, "You should take every opportunity to limit the propaganda benefit the IRA will reap from the outbreak ... The Government regard the outbreak most seriously."
In a speech that was written but never recorded, the Queen urged her "brave country" to stand firm as it faces up to the "madness of war" with a nuclear-armed Soviet Union.
Papers released by the National Archives include the remarkable script drawn up by officials as part of a Whitehall war-gaming exercise, designed to work through potential scenarios if the Cold War ever became something more.
In the speech, dated March 1983, the Queen stated that while the dangers were "greater by far than at any time in our long history", she appealed to people to remember the qualities which saw them keep freedom alive through two 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," she declared. "May God bless you all."
William Hague's first attempt to enter politics was blackballed by then-Prime Minister Margaret Thatcher, newly-released Government papers show.
Mrs Thatcher had been among those cheering the future Foreign Secretary when, as a 16-year-old schoolboy, he delivered a speech that took the Conservative Party conference by storm.
Mrs Thatcher was less impressed when - as a 21-year-old Oxford graduate - he tried to secure a prestigious posting as special adviser to the Chancellor.
Papers released by the National Archives at Kew, west London, show she angrily blocked the move, denouncing it as a "gimmick" and an "embarrassment" to her Government.
When senior Treasury official John Kerr requested approval for his appointment in a letter dated March 17 1983, Mrs Thatcher scrawled across the top in thick black ink, "No [triple underlined] - this is a gimmick and would be deeply resented by many who have financial-economic experience."
Edward VIII was bugged by the government during his final days as King, according to official files made public.
Home Secretary Sir John Simon instructed the General Post Office to secretly record the King's telephone calls during the 1936 abdication crisis, papers held in the Cabinet Office for more than seven decades showed.
Wallis Simpson, the King's divorced American mistress, was in France while calls between royal residences and "the continent of Europe" were recorded.
In November 1936, Edward, who had yet to be crowned, told Prime Minister Stanley Baldwin he intended to marry Mrs Simpson. At that time the Church would not remarry a divorcee when their previous partner was still alive.
The King had hoped to survive the crisis but on December 10 1936 he signed the instruments of abdication ending a reign that lasted only 326 days.