There were no reports of casualties in the blast, in Earl's Court, which happened half an hour after a warning call using a recognised code word was received by the Associated Press news agency. The caller claimed to be from the IRA.
The explosion occurred just before 10pm at an empty house in The Boltons, an expensive residential area. Windows were blown out of the house and in neighbouring buildings. Police cordoned off surrounding streets.
Local resident Winnie Gordon Strauss, who was out walking her dog when the bomb went off, said: "I've still got glass in my hair." Peter Roscow, 40, a business consultant, was at home in Collingham Road when he heard what he said was quite clearly a bomb going off.
He said: "It seemed it was much closer than it was. But I remember back in the Seventies when there was an IRA bomb - these things can be very deceptive."
Police immediately converged on the area and began checking beneath cars for further devices, although a brief stand-off was observed because of fears of further devices.
The explosion came just one day after the inquest on IRA terrorist Ed O'Brien, who killed himself last February when a bomb he was carrying exploded prematurely on a bus in Aldwych, central London.
Last night's explosion happened less than half a mile from the site of a similar blast on 8 March. Then, a bomb was placed in a rubbish bin outside the gates of Brompton Cemetery near the Earl's Court Exhibition Centre. There were no casualties, but cars and property were damaged.
Security sources have recently suggested that although the IRA has been quiet in Northern Ireland the chances of further attacks in London were high. A "phoney war" has been in effect since the bombings in London heralded the end of the IRA's 17-month ceasefire.
Those attacks were followed by a series of belligerent IRA statements, but earlier this month the organisation's Easter message was unexpectedly temperate.
The fact that there had been no attacks in Northern Ireland allowed hopes to develop that the series of attacks in February represented a discrete sequence which might not necessarily mean a full-scale resumption of violence.
At the same time, however, the IRA mistrust of the British Government has been running at a particularly high level, and there have been no signs of a renewed ceasefire.
There had been some early hopes of a new ceasefire, which would allow Sinn Fein to take part in the political negotiations which are due to start in Belfast on 10 June. But these have faded as the poor atmosphere has persisted, with most observers reckoning that the talks are most likely to open without Sinn Fein. The party will, however, probably contest the elections, which are due to take place on 30 May.
In the meantime, the general assumption has been that the absence of violence, though welcome, was unlikely to last for much longer. No one was sure, however, when a fresh attack might come. Gerry Adams, the Sinn Fein President, said recently that the situation was difficult to interpret, adding: "One could hear on the next news broadcast reports of some IRA operation."Reuse content