Police forensic officers in 1982 working on the remains of the IRA car which contained the Hyde Park bomb. PA Archive / PA Images PA Archive / PA Images / PA Images

THE HYDE PARK bomb caused a “significant explosion” and was intended to “maim and kill”, a leading expert has told the High Court.

Forensic explosives expert Kim Simpson gave evidence during the first day of a trial in London to determine whether convicted IRA member John Downey is liable for the bombing.

Simpson examined evidence from the scene of the 1982 blast, in which four members of the Royal Household Cavalry were killed and 31 other soldiers and civilians were injured.

She told the court: “This was a very significant explosion, it was a major event.”

The bomb, a radio-controlled improvised explosive device (IED), was planted in a blue Morris Marina which she said had “disintegrated” with the force of the blast.

She said that, in her opinion, the bomb was planted by the provisional IRA because items found at the scene matched those found at other incidents the terrorist group had claimed responsibility for.

John Downey PA Images PA Images

She told the court: “During the 1980s the provisional IRA were considered to be the world leaders, if you like, in IEDs.

“They were the most sophisticated terrorist group out there.”

Simpson, who has investigated a number of incidents during her 32-year career, including the London 7/7 bus explosion in Tavistock Square in 2005, said the radio-control technology at the time meant whoever detonated the bomb would have needed a “line of sight” to the target.

She also explained how the bomb was made with the explosive substance frangex, a type of gelignite, and contained more than 27lbs of nails.

Simpson said: “There is only one purpose to putting shrapnel into an IED and that is to increase the lethality of the device – to maim and kill specifically.”