The secret plot to kill the Queen.

Recently declassified documents revealed plans to assassinate Queen Elizabeth II during her tour of California just over 40 years ago. 

The late royal and her husband Prince Philip were invited by then-President Ronald Reagan to see his home state. 

A few weeks before authorities were alerted of an alleged sympathiser of the Irish Republican Army that wished for her death.

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The royal couple spent a week exploring California after arriving on the Royal Yacht Brittania on February 26, 1983. 

According to a report by the FBI, in February 1983, a San Francisco Police officer was contacted with a tip-off about members who attended the Dovre Club. The club was a well-known 'republican bar' known for customers that were sympathisers of the Provisional Irish Republican Army (PIRA). 

The report claimed the unidentified patron had told the officer his daughter "had been killed in Northern Ireland by a rubber bullet". As such, he had plans to harm the British monarch.

Image: Getty.

"The man claimed he was going to attempt to harm Queen Elizabeth and would do this either by dropping some object off the Golden Gate Bridge when it sails underneath or would attempt to kill Queen Elizabeth when she visited Yosemite National Park," the documents read. 

The report said the Secret Service planned to close the walkways on the Golden Gate Bridge when the Queen's ship neared.

The royal couple's visit to the United States occurred in the middle of The Troubles, a 30-year-long conflict in Northern Ireland that divided unionists and nationalists over whether Northern Ireland should stay within the U.K. or join the Republic of Ireland. 

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Tragically over 3,500 people were killed in civil rivalry, including Prince Philip’s uncle Lord Louis Mountbatten. 

The Lord was assassinated by an IRA bomb in 1979. Fortunately, The Troubles came to a close after the Good Friday agreement was signed in 1998.

Despite the threat, the FBI reported that Queen Elizabeth’s visit to California wrapped "without incident," and the case was closed.

Feature Image: Getty.