Home Affairs Correspondent.
With last night's blast in London's Docklands, the IRA has resumed its attack on the capital's commercial centres.
It was three years ago when London last witnessed similar scenes of devastation. A huge bomb blew apart the heart of the City killing one, injuring 40 and causing pounds 1bn of damage.
But the terrorists' determination to bring their grim message to mainland Britain and the centre of both political power and wealth goes back over 23 years - and people rather than buildings have often been the target.
In March 1973 two car bombs blew up outside the Old Bailey killing one and injuring 170. The following year terrorists blew the roof of Westminster Hall, injuring five.
Three months later, in October 1974, they brought carnage to Guildford, killing five and injuring 50 by bombing two pubs frequented by soldiers. In November the same team killed two outside Woolwich barracks in south London. The next month, they repeated the dreadful exercise in Birmingham, killing 21 and injuring many more.
The following year, they shot dead Ross McWhirter, co-founder of the Guinness book of Records, and a vociferous IRA opponent.
It was four years before they claimed their next victim - the Shadow Secretary of State for Northern Ireland Airey Neave. The Tory spokesman was killed by a car bomb close to the House of Commons.
Two years later in October 1981, a coach of Irish Guardsmen were the targets of a 30lbs bomb loaded with metal bolts. Several were badly hurt and two passers-by were killed.
In 1982, at the height of a particularly brutal campaign, two radio-controlled bombs in the Royal Parks killed 11 soldiers, seven horses and injured 50 others. The following year, active service units turned their attentions to commerce - a bomb at Harrods in Knightsbridge killed six and injured 93.
About a year later they scored what was, in their eyes, one of their biggest triumphs. The IRA managed to explode a bomb in the Grand Hotel, Brighton during the Conservative Party Conference. Lady Thatcher, then Prime Minister, escaped but five were killed and dozens more injured, many of them seriously.
Four years later they had returned their attentions to the military, killing one man at Inglis Barracks in Mill Hill and 11 more at Deal in Kent.
In 1990, Ian Gow, a supporter of the Ulster Unionists, was killed by a car bomb, and an army careers office, the Stock Exchange and the upmarket Carlton Club were the focus of small devices.
In 1991, they targeted John Major, firing mortar bombs at Downing Street.
Two young boys, Jonathan Ball, aged three, and Tim Parry, 12, were killed by a bomb in Warrington on 20 March, the following year.
And perhaps prompted by the outrage at the deaths of two such innocents, it was later that year the IRA started hitting at commerce. A huge bomb rocked the Baltic Exchange, in the City, which killed three, injured 90 and caused an estimated pounds 800m of damage.
The same year, two IRA gunmen hijacked a minicab and forced the driver to take explosives to Downing Street, but they exploded in Whitehall.
In 1993 a series of small devices were set off in London's West End causing more chaos than major damaged . It was in April that year they devastated the City.
The IRA's last efforts before the ceasefire included three mortar attacks at Heathrow, which caused only minor damage.Reuse content