No one was hurt but the attacks showed that the IRA is stepping up its campaign. It is the first time a bomb has been planted inside a train carriage in England, showing an increased willingness by the terrorists to risk civilian casualties.
The first bomb went off on the 9.05am Victoria to Ramsgate train which was stopped at Kent House station in Penge, south- east London, after warning calls were received. More than 70 passengers were evacuated and the train was badly damaged.
The second bomb exploded at South Kensington Tube station just before 3.30pm. Warnings had been received 14 minutes previously and the station was evacuated before the bomb went off.
Planting a bomb among passengers on a moving train shows a hardening of terrorist attitudes. The IRA has repeatedly attacked railway stations, track and signalling equipment.
Incendiary devices have been planted on trains and the London Underground system and in one case two passengers were injured when a train went over a bomb.
Geoff Harrison Mee, divisional director of Network SouthEast, said: 'This could have been very serious. If anyone had been in the carriage when the device exploded there would have been carnage.'
Three telephone warnings claiming that there were two bombs aboard the Ramsgate train were given just moments before it left Victoria but it was too late to stop its departure.
The terrorists claimed that the bombs would explode in 30 minutes and the driver of the train was told to make an unscheduled stop at Kent House station. It pulled up at 9.22am and the passengers were evacuated.
A Network SouthEast spokesman said: 'The train was diverted on to a loop at the back of the station where, when it pulled to a halt at the platform, the staff quickly made sure all the passengers were off.'
The bomb, which had been planted in the seventh out of 12 carriages, exploded 17 minutes later. Windows were blown out, seats damaged and the interior of the 30-year-old train was scorched by the blast.
Passengers continued their journey by bus and last night British Transport Police appealed to them to telephone 0800-789 321 with information about anything they might have seen on the train.
Other train services on the line were halted, causing major disruption, and 285 pupils were evacuated from Royston primary school near the station before the explosion. There was no second bomb found on the train.
The line was reopened in time for the rush-hour last night and Network SouthEast was hopeful that Kent House station would reopen today.
The second explosion occurred at South Kensington Tube station five-and-a-half hours later. Two telephone warnings from a man with an Irish accent were received giving London Underground 20 minutes to clear the area.
The station, which remained closed last night, was not expected to be reopened until today. Two hundred people were evacuated from the terminal and the bomb went off 14 minutes after the last call had been received. There were no casualties but services on the District, Circle and Piccadilly lines were badly disrupted.
Chief Superintendent Peter Kruger said that the bomb had gone off in a disused shaft between the Piccadilly Line and District Line platforms. It is thought to have been a small device which damaged brickwork but not the platforms or track.
Later, further disruption was caused when Monument and Bank Underground stations in the City of London were closed by telephoned bomb warnings and parts of the Central and Northern lines were also suspended.
Although recognised code words were used no devices were found.