Officers recovered enough Semtex high explosive for about six small "bag bombs", along with timers, fuses, wiring and documents belonging to the bombers. The terrorists from the IRA unit had fled, but the police believe that the seizure is an important breakthrough.
The operation was one of a series of raids made at addresses in London from midnight to the early morning yesterday.
The success followed information obtained from the body of the terrorist who died after his bomb accidentally exploded while on a double-decker bus in central London on Sunday. Police believe that the dead man was Edmund O'Brien, 23, from Gorey, Co Wexford.
Last night Irish newspapers published a photograph of Mr O'Brien as a 12-year-old school boy. His home was examined by police yesterday.
Information was also provided following the deactivation of a bomb left in a bag in a telephone box in Charing Cross Road, in the West End of London, six days ago. In both cases a 4lb to 5lb Semtex device was used.
Anti-terrorist officers believe the bom bs were made at the house raided yesterday. But they have ruled out any links with the unit responsible for the 500lb fertiliser bomb that devastated Docklands in east London and killed two people.
Security sources also believe that the IRA has several active-service units ready to continue the new bombing campaign, which may now be extended to cities outside London.
Commander John Grieve, head of Scotland Yard's anti-terrorist branch, said of yesterday's seizures: "We have recovered significant amounts of explosives and bomb-making equipment. Inquiries and forensic evidence gathering are continuing."
Anti-terrorist officers are seeking details of the man who died when the bomb went off on the 171 bus.
Two men arrested in south London on Monday morning under the Prevention of Terrorism Act following the Aldwych explosion were released yesterday without charge.
Meanwhile, it has emerged that an Irishman who was previously under police guard in hospital following the Aldwych bus blast is no longer being regarded as a suspect.
Armed officers who had been standing guard over Brendan Woolhead, 33, at St Thomas's Hospital, where he is being treated for serious injuries to his pelvis and skull received in the bomb blast, were removed yesterday afternoon.
Earlier his relatives and neighbours in the Finglas suburb of Dublin insisted he had no links with the Irish republican movement. Finula Green, Mr Woolhead's sister-in-law, spoke of the "very frightening" reports that he had been under armed police guard in hospital.Reuse content