The chaos began at 8am with telephone messages to two hotels at Walsall, close to junction 9 of the M6. A similar call was made to an organisation in Warwickshire. The messages contained an IRA password and a warning which prompted a security operation involving bomb disposal experts and four Midlands police forces.
Thousands of motorists were diverted on to A-roads as the M1 was closed between junctions 17 and 19 in Northamptonshire and at junction 20 in Leicestershire. In the West Midlands, police closed the M6 between junctions 7 and 10 in both directions, and the M5 was also shut in both directions from junction 1 to its intersection with junction 8 of the M6.
Police sealed off 30 miles of motorway and sniffer dogs, firearms officers and explosive experts began scouring the carriageway as a police "Skyshout" helicopter warned motorists away from the area.
Bomb disposal experts carried out two controlled explosions on a cardboard and a metal container placed among roadworks on the A428 which runs under the M1. Further north, West Midlands Police evacuated 500 people from their homes in Walsall. Just before 3pm another controlled explosion was carried out near junction 9 of the M6.
As a terrorist operation it had been so simple and effective in causing disruption and economic damage that it begged the question: why had the IRA not used the tactic before?
In a research paper published in July last year, Professor Paul Rogers, head of Peace Studies at the University of Bradford, predicted the IRA's renewed mainland campaign would concentrate on key economic targets, notably transport links. He said motorways were logical targets because they now carried so much freight.
The 1992 bombing of Staples Corner, the London junction at the start of the M1, was a precedent, he said.
Security experts said yesterday that the episode - following on from the recent targeting of the rail network - signalled a worrying change in tactics by the terrorists. The move away from city-centre bombings to soft infrastructure targets was seen as evidence that the IRA was no longer worried about losing the sympathy of the British people.
James Wyllie, a senior lecturer in strategic studies at the University of Aberdeen, said: "Perhaps they reckon that since the breakdown of the ceasefire there is no residual sympathy for them among the British people and they are in a no-lose situation."
He said that the campaign was clearly designed to put Northern Ireland at the top of the agenda of an incoming Labour government. How the British public will react remains to be seen.Reuse content