Duncan Black reviews the route to the brink of a terror campaign

THE explosion which last night blew apart a double-decker bus in London has heightened fears of a renewed and intense IRA campaign of terror on the British mainland.

Although the IRA has not yet claimed responsibility for the latest blast, it is the third time a bomb has been planted in London since they declared an end to their ceasefire on the evening of Friday, February 9.

Within an hour of that announcement, the terrorists put those chilling words into action by detonating a bomb at Canary Wharf in the Docklands area, killing two people and injuring more than 100.

It has since transpired that the bombers behind that outrage used Scotland as a gateway. It is believed that a flat-backed vehicle which travelled from Larne to Stranraer had the explosives on board as it crossed the Irish Sea and was driven off into Scotland.

Police believe the lorry disembarked at Stranraer on February 7, two days before the Docklands bombing. It was next spotted in Carlisle and detectives are trying to trace its movements on February 8 there, or in other areas, before it was next seen in the South of England.

A reward of up to #1m has been offered, apparently by a group of insurance companies, for the capture and conviction of those responsible for the Docklands blast. In a determined drive to capture the killers, police visited 40 addresses in dawn raids in England.

The Docklands bombing brought dread back into the hearts of the citizens of Northern Ireland, who had quickly become used to the long-forgotten feeling of peace in their daily lives during the precious 17 months of the ceasefire, and spelled fear for people working and living in London facing the prospect of a renewed mainland bombing campaign.

Within a few days, the fears of Londoners proved justified as the IRA vowed to continue its campaign ``as long as is necessary'' and planted a bomb in a plastic holdall in the heart of the capital's theatreland, in Charing Cross Road near the junction with Shaftesbury Avenue.

That bomb was defused successfully by police but caused chaos as a large area of the city centre was closed off, with shops shut down and streets sealed off. The square mile covered by the police cordon stretched from the north side of Trafalgar Square to Oxford Street, from Piccadilly Circus to Covent Garden.

Then came last night's explosion in the same area of the city. Early this morning, it was still not known if the IRA was responsible for this blast. Significantly, there was not the usual advance coded warning. Also unusually, the bomb was planted on a bus apparently carrying ordinary members of the public.

If last night's blast does prove to have been a deliberate attack, it is sure to go down as one of the most callous and senseless even in the history of the Ulster conflict.

It would not, though, be the first time terrorists had bombed a moving vehicle. However, in previous incidents the victims were soldiers.

On February 4, 1974, 12 people died when a bomb exploded on a coach packed with soldiers on the M62 near Leeds.

In June 15, 1988, six soldiers were blown up in their van after taking part in a charity fun run in Lisburn, County Antrim.

On August 30, 1988, at Ballygawley, eight soldiers were killed and 27 were injured when the IRA blew up the bus taking them back to base in County Tyrone after leave in England.

The fact the victims of this incident would appear to have been civilians, combined with the apparent absence of any warning call, suggest another possibility - that last night's explosion was some sort of dreadful accident.

It could be that a bomb had been abandoned by a terrorist transporting it to a target destination. It could even be that a terrorist may still have been aboard the bus when the device detonated.

The IRA has a long history of similar blunders.

In April 1989, Ms Joanne Reilly, a 20-year-old Catholic shop assistant, was killed and 34 people were injured when an IRA bomb exploded prematurely at a police station in Warrenpoint, County Down. The IRA telephoned a warning nine minutes after the device exploded.

In July 1988, Catholics Eamon Gilroy, 28, and Elizabeth Hamill, 64, were killed outside a Falls Road swimming pool in west Belfast by a bomb intended for security forces.

In August 1988, the IRA apologised when a boobytrap bomb, intended for security forces, killed Catholics Sean Dalton, 55, and Sheila Davis, 60, on the Creggan estate in Londonderry. Mr Gerry Curran, also a Catholic, was injured and died later in hospital.

In November 1988, Mr Barney Lavery, 67, and his granddaughter Eamma, 13, both Catholics, were killed by a bomb while driving past the RUC station at Benburb, County Tyrone.

In October 1989, RAF Corporal Maheshkumar Islania, 34, and six-month-old daughter Nivruti were shot dead as they left a restaurant in Wildenrath, West Germany. An IRA statement expressed ``profound regret'' and insisted the gunmen were unaware of the baby's presence.