Twenty years ago today, Parliament was getting ready for its annual renewal of the Prevention of Terrorism Act, which was largely designed to combat the threat from Irish paramilitary groups. There was little chance that MPs would vote against it, although the opposition would still make a token stand just on the general principle that they were the opposition. The news would doubtless be buried in the dismal middle pages of the next day's newspapers.
But not this time.
Late in the afternoon, a red Nissan Micra drove into the car park of the Excelsior Hotel at Heathrow. Inside were enough explosives to give the airport a really bad day. But they weren't intended to be used in a car bomb, for the car also carried a set of disposable mortar tubes.
Between 17:05 and 17:15, six major news agencies were called and a bomb threat was made using recognised code words. "Clear all runways," went the warning. "Stop all flights."
They didn't clear the runways. They didn't stop the flights. Instead, the authorities began a search, working on the assumption that the bombs - if they existed - were already in place.
At 17:40, a Concorde touched down after a flight from New York. At 17:57, four mortar bombs were fired at the runway. None of them exploded, though one shattered into pieces. Planes kept on using the runway, oblivious to the danger. It would take another forty minutes before the runway was closed and a search for the mortars began. The security services were not at their most efficient on this day in 1994.
The only explosion was back at the car park of the Excelsior Hotel. The Nissan Micra was almost completely destroyed when the mortars were launched, and cars around it were set on fire. Black smoke spilled into the sky. But not everyone had their daily routine immediately shattered; staff at the nearby Ramada Hotel couldn't hear the detonation because of the noise of ongoing refurbishment.
The vote in Parliament went ahead, and the Prevention of Terrorism Act was duly renewed. No one was hurt in the attack, and the only damage was the disruption to flights while the runway was cleared. This was lucky for Heathrow, as these home-made mortars had often been used in Northern Ireland to lethal effect; like the security services, the IRA were not at their most efficient in this attack. But then they probably never intended to be.
Their true purpose was a political one. The Provisional IRA were saying: sure there's a peace process, but it's not going the way we want, so remember that we can still strike at will. The Troubles might have been about to transfer to the political sphere, but the combatants wanted to enter that sphere with as much advantage as possible from their days of violence. Attacking such a massively symbolic target as the busiest airport in the world just hammered the point home.
Similar attacks would happen again twice during March, both targeted at Heathrow. It didn't end the peace process; it just reminded everyone how much hard work still needed to be done to keep the bombers and killers from going back to their old ways.