At 3 a.m. on the morning of Saturday, February 18, 1978, Rev Roy Magee called to a house in east Belfast to find two young girls, aged 11 and 12, waiting up for their parents to come home from a night out. Paul and Dorothy Nelson were attending a function in the La Mon House Hotel.

Rev Magee was hoping to find the Nelsons in their home. He knew that an IRA bomb had exploded in the hotel six hours earlier, and had already accompanied survivors to hospital. When he found young Andrea and Melanie alone, he feared the worst.

"When they heard the car, they came running to open the door of the house," he recalls. Andrea, the older girl, told Rev Magee that they had heard about the bombing. When she rang a special information number for people inquiring about relatives, she was told nobody was seriously injured.

"I told them that there were a lot of people unaccounted for, but said I'll keep looking through the night," Rev Magee said. He asked if they would like to spend the night in his house. "They said `No, because wherever Mum and Dad are, they will phone'."

As time passed, it became clear that the Nelsons would not be phoning or coming home.

Twelve people - seven men and five women, all Protestants - died in horrific circumstances, burned in a massive fireball. They were attending the annual dinner dance of a dog club. Thirty more were injured in the explosion, caused by a bomb containing a pound of home-made explosives and four gallon tins of petrol.

Rev Magee described the scene as an inferno. People were trapped inside the building as the fire spread, and eyewitnesses described people running from the hotel with their clothes and hair on fire.

"People started being brought out, without legs and arms, and I knew it was far worse than I first thought," one man told the Belfast Newsletter. The bodies of the victims were so badly charred that they had to be identified by dental records, blood group details and jewellery found on the corpses.

Initially it was thought that a number of children were among the casualties because of the degree of mutilation of the bodies.

In the case of the Nelsons, Rev Magee says: "By a process of elimination, by about the Wednesday, it was disclosed that what was left in the mortuary, what pieces of charred bone were left, was probably Paul and Dorothy Nelson."

The reaction to the bombing was widespread revulsion. It had resulted in the highest death toll from an explosion since loyalists bombed McGurk's bar in north Belfast in 1971, killing 15 people.

A telephone warning was given less than a minute before the explosion. The IRA, in a statement of admission, claimed a nine-minute warning had been given, and accepted this was "totally inadequate given the disastrous consequences".

Accepting that "12 innocent people" had died, the statement continued: "We accept condemnation and criticism from only two sources: from relatives and friends of those who were accidentally killed, and from our own supporters who have rightly and sincerely criticised us."

The then-SDLP leader, Gerry Fitt, called on everyone to give information on the "depraved animals" who had planted the bomb to the police. The Pope, in a message sent through the Vatican secretary of state, described the attack as "an inhuman deed".

The Northern Secretary at the time, Roy Mason, said the bombing ranked "in cold senseless brutality with anything in the annals of international terrorism".

More than 30 people were arrested in Republican areas of Belfast in the days after the bombing. Among those detained was Gerry Adams, now Sinn Fein president. He was never connected to the attack, but was charged with IRA membership. Mr Adams was later cleared when the case was dismissed due to lack of evidence. A west Belfast man subsequently served a life sentence for the manslaughter of the 12 La Mon victims.

Rev Magee, a personal friend of Paul and Dorothy Nelson, conducted their funeral service. The Nelson girls both left Northern Ireland shortly after the bombing to live with an uncle in England, where they still live. Many other survivors of the bombing also later emigrated.

"I actually felt that it would be a watershed, that things couldn't get any worse, that surely the fact that people had been killed who were unquestionably innocent, would mean that everybody would take a step back and begin to look at their actions," Rev Magee says. "Unfortunately there have been many others killed in a senseless way since then."