Media playback is unsupported on your device Media caption How the second missile crisis unfolded

Contrary to popular belief, the Cuban missile crisis did not end with the agreement between the US and Soviet Union in October, 1962. Unknown to the US at the time, there were 100 other nuclear weapons also in the hands of Cuba, sparking a frantic - and ingenious - Russian mission to recover them.

In November 2011, aware that the 50th anniversary of the most dangerous few weeks in history was less than a year away, my Russian colleague Pasha Shilov and I came across several new accounts that changed our perspective on the Cuban missile crisis and how much we thought we knew about it.

Growing up in Berkshire, England, through the nuclear paranoia of the 1980s, with Ronald Reagan's Cruise and Pershing missiles stationed only 30 miles away from my family home, I was inculcated with a keen awareness of Cold War brinkmanship.

Pasha grew up in Moscow and described how it was from the Soviet point of view - equally frightening by his account.

But what we've now learned about the chilling events of October and November 1962 has put our own experiences into perspective - and maybe given rise to a few more grey hairs along the way.

Nuclear disaster averted Image caption The crisis sparked protests worldwide Cuban missile crisis ignites when, fearing a US invasion, Castro agrees to allow the USSR to deploy nuclear missiles on the island

The crisis was subsequently resolved when the USSR agreed to remove the missiles in return for the withdrawal of US nuclear missiles from Turkey Timeline: US-Cuba relations BBC Archive: Cuba and the Cold War

Our investigations took us to St Petersburg and the Soviet Submariners Veterans' Society via the National Security Archive in Washington DC, where Svetlana Savranskaya, the director of the Russian archives, told us an incredible story.

There had been a second secret missile crisis that continued the danger of a catastrophic nuclear war until the end of November 1962.

This extended the known missile crisis well beyond the weekend of 27-28 October, the time that had always been thought of as the moment the danger finally lifted with the deal between Kennedy and Khrushchev to withdraw the Soviet missiles in exchange for a US promise not to invade Cuba.

The secret missile crisis came about through an unnerving mix of Soviet duplicity, American intelligence failures and the mercurial temperament of Fidel Castro.

The Cuban leader, cut out of the main negotiations between the superpowers over the fate of the long range Soviet missiles stationed in Cuba, began to cease cooperation with Moscow.

Fearing that Castro's hurt pride and widespread Cuban indignation over the concessions Khrushchev had made to Kennedy, might lead to a breakdown of the agreement between the superpowers, the Soviet leader concocted a plan to give Castro a consolation prize.

The prize was an offer to give Cuba more than 100 tactical nuclear weapons that had been shipped to Cuba along with the long-range missiles, but which crucially had passed completely under the radar of US intelligence.

Khrushchev concluded that because the Americans hadn't listed the missiles on their list of demands, the Soviet Union's interests would be well served by keeping them in Cuba.

Kremlin number two, Anastas Mikoyan, was charged with making the trip to Havana, principally to calm Castro down and make him what seemed like an offer he couldn't refuse.

Mikoyan was forced to use the dark arts of diplomacy to convince Castro

Mikoyan, whose wife was seriously ill, took the assignment knowing that the future of relations between Cuba and the Soviet Union were on the line. Shortly after arriving in Cuba, Mikoyan received word that his wife had died, but despite this, he pledged to stay in Cuba and complete negotiations with Castro.

In the weeks that followed, Mikoyan kept the detail of the missile transfer to himself while he witnessed the mood swings and paranoia of the Cuban leader convinced that Moscow had sold Cuba's defence down the river.

Castro particularly objected to the constant flights over Cuba by American surveillance aircraft and, as Mikoyan learned to his horror, ordered Cuban anti-aircraft gunners to fire on them.

Knowing how delicate the state of relations were between the US and Russia after the worst crisis since World War II, US forces around the world remained on Defcon 2, one short of global nuclear war until 20 November.

Mikoyan came to a personal decision that under no circumstances should Castro and his military be given control of weapons with an explosive force equal to 100 Hiroshima-sized bombs.

He then extricated Moscow from a seemingly intractable situation which risked blowing the entire crisis back up in the faces of Kennedy and Khrushchev.

Image caption Anastas Mikoyan (far right, in 1938) took the all-important mission

On 22 November 1962, during a tense, four-hour meeting, Mikoyan was forced to use the dark arts of diplomacy to convince Castro that despite Moscow's best intentions, it would be in breach of an unpublished Soviet law (which didn't actually exist) to transfer the missiles permanently into Cuban hands and provide them with an independent nuclear deterrent.

Finally after Mikoyan's trump card, Castro was forced to give way and - much to the relief of Khrushchev and the whole Soviet government - the tactical nuclear weapons were finally crated and returned by sea back to the Soviet Union during December 1962.

This story has illuminated a chapter in history that has been partially closed for the past 50 years.

But it leaves us with a great respect for Mikoyan and his ability to judge and eventually contain an extremely dangerous situation which could have affected many millions of people.

Joe Matthews is a producer for Wild Iris TV, which has made a short film about the "secret" Cuban missile crisis