The assassination attempt on King Charles III that almost worked

• On the podcast | Spying in the Troubles: the murky world of double agents in Northern Ireland

“The most famous spy [in the conflict] was someone called Sean O'Callaghan,” says Hemming. O’Callaghan served within the IRA, but from the late-1970s onwards, he worked as a mole within the organisation, relaying information back to the Irish government and MI5.

And it’s thanks to O’Callaghan, says Hemming, that the British monarch, King Charles III, is alive today.

Who was O’Callaghan and how did he get involved in the IRA?

O'Callaghan, born into a republican family in Tralee, County Kerry, was drawn to the IRA early in The Troubles, believing that the IRA's fight could spark a revolution across Ireland.

By the 1970s, he was part of an IRA unit in Northern Ireland, carrying out attacks such as mortar bombings. However, disillusioned by the growing sectarianism within the IRA, O'Callaghan left the organisation in 1976.

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When the IRA contacted him three years later, he saw an opportunity: he had already been in touch with the Irish police and offered to become an informant. So, feigning a return to the IRA, O'Callaghan became a double agent.

O’Callaghan was part of an active IRA service unit that devised the plan, says Hemming. “Their plan was to plant a bomb in a bathroom behind the royal box in a theatre where they knew that Charles and Diana would be going to attend a concert.”

This wasn’t just any run-of-the-mill royal engagement for the then-Prince and Princess of Wales. “This was going to be a concert for The Prince's Trust,” says Hemming. “And the headline act was set to be Duran Duran.”

The attempt to kill Prince Charles and Diana at a Duran Duran concert

In the early 1980s, the British pop rock band Duran Duran was at the very peak of its international success, having released a smash-hit album ‘Rio’ in 1982, followed up with ‘Seven and the Ragged Tiger’ in 1983.

The would-be assassins knew that by targeting leading British public figures at such a high-profile event, the world’s focus would be drawn back onto the ongoing conflict, and the IRA.

Additionally, as Sean O’Callaghan notes in his 1998 autobiography, The Informer, it also would have meant that “Anglo-Irish relations would sink to a new low.”

But the IRA made a crucial mistake when planning the assassination: they gave O’Callaghan a key task in the plot – planting the bomb and then tiling it up inside the bathroom so nobody could see it.”

Of course the bomb was never planted – O’Callaghan was already a spy. “He was reporting to the Irish police, and very soon he'd be reporting to MI5 as well,” says Hemming.

Other IRA assassination plots

While audacious, the plan was in keeping with the IRA’s previous action, suggests Hemming. The 1983 attempt came almost four years after the assassination of Earl Louis Mountbatten – relative of the British royal family – by the IRA. Such high-profile, visible violence was a well-worn tactic for the IRA.

But how close did the plot come to killing the royals? If O’Callaghan hadn’t been given the assignment, would the plan have worked?

According to Hemming, the answer is yes.

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“This technology would've worked, because the IRA would use almost identical technology to plant a bomb the following year in Brighton.” In October 1984, the IRA planted a bomb in the Grand Hotel in Brighton, that very nearly killed Margaret Thatcher.

What happened to O’Callaghan afterwards?

As for O’Callaghan’s life after the plot, he returned to England and confessed to committing murders when an active IRA agent.

He spent years in imprisonment before being released in 1996, publishing a book about his experiences just over a year later.

In 1997, he was confirmed as a valuable informant and even received a pardon from the Queen, then advising David Trimble, a key figure in the Good Friday Agreement.

He died in 2017, aged 62.