John Downey, a 61-year-old Donegal man, has been charged with the 1982 IRA attack on the Queen’s cavalry in Hyde Park, London. The nail-bombing at the tourist attraction killed four police officers and seven horses.

The British authorities declined to explain how Downey's arrest, at London’s Gatwick Airport, came about almost 31 years after the attack. He is charged with four charges of murder and conspiring to cause an explosion. The four members of the Household Cavalry who were murdered were Roy John Bright, Dennis Richard Anthony Daly, Simon Andrew Tipper, and Geoffrey Vernon Young.

Sinn Fein official Gerry Kelly called Downey’s arrest “vindictive, unnecessary and unhelpful” and an act of “bad faith,” the Associated Press reports.

The Irish nationalist political party called for Downey’s release accusing the British Government of violating the Good Friday peace agreement, by pursuing Downey who was on a list of IRA suspects, “on the run.” They added that the British Government should no longer be pursuing IRA suspects.

In a statement Kelly said "The decision to arrest and charge him in relation to IRA activities in the early 1980s is vindictive, unnecessary and unhelpful. It will cause anger within the Republican community.

He continued "This development represents bad faith and a departure from what was previously agreed by both governments."

Anti-terrorist police in London have continued to investigate unsolved IRA murders. From 1970 to 1997 the Provisional IRA killed nearly 1,800 people.

These investigations go against the agreements made after the Provisionals renounced violence and disarmed in 2005.

Kelly, who led the IRA’s car-bombing attacks in London, in 1973, said Downey was informed in 2007 that he was no long wanted for questioning by the British police.

Downey is the third man to face trial for this crime.

On July 20, 1982, the British troops were engaged in entertainment and ceremonial duties at Hyde Park. The bomb planted in a parked car was detonated by remote control as the troops moved towards Buckingham Palace.

Two hours after this attack a suitcase bomb close to Regent’s Park killed seven army musicians. Witnesses said the musicians were blown into the air. Twenty-two others were injured.

These attacks represent one of the IRA’s biggest killings of British troops.

If convicted Downey would face parole in two years under the Good Friday Agreement.

The BBC reports that last year a survivor of the IRA attack at Hyde Park, suffering from post-traumatic stress, fatally stabbed his children before killing himself. Ex-Army sergeant Michael Pedersen’s children Ben and Freya, aged seven and six, were found near Andover, Hampshire, in September. Pedersen (51) was the Household Cavalry rider on Sefton, the horse who famously survived the bombing.