Sir Paul Condon, Metropolitan Police Commissioner, said precautions taken in London for the past decade have assumed terrorists would make sure they gave themselves time to escape after planting a bomb.
He also announced immediate round- the-clock armed police security for more than 100 key buildings associated with Israel and the Jewish community in the wake of the two car bombings in two days in the capital. This protection includes surveillance and parking bans for more than 100 buildings, and increased security for hundreds of other sites.
Sir Paul said the police now faced a 'new dimension' given the power and ferocity of the two bombs. Both were estimated to be 30 pounds of high explosive. He said a terrorist prepared to trigger a device within moments of delivering it to the target, as occurred at the Israeli embassy in Kensington Palace Gardens, central London, and in Finchley, north London, was a 'potential suicide bomber'.
He also defended his force against criticism of its failure to stop the second bomb only 13 hours after the first.
Brigadier-General Azriel Nevo, Israel's military attache to London, said on Israeli radio that authorities in Britain had 'blundered'. He said that after the embassy bomb 'our people gave their evaluation to the British authorities that there was a danger now to the Jewish institutions and, here you are - there was a (second) blast in the middle of the night'.
However, Sir Paul insisted: 'We are at one with the Israeli agencies involved, and we are working in partnership with them to prevent any further terrorist attacks in London.'
He said the warnings had been proved correct 'with hindsight', but his information was that all requests from the Israeli government, but not other Jewish groups, had been acted on.
Security sources revealed last night that M15 had carried out a 'threat assessment' on the risk of attack by Islamic extremists on targets in London and concluded that there was a real possibility of a terror campaign in Britain.
The warning, which was part of a continuous programme of surveillance and assessment, would have been sent to the Metropolitan Police and government departments, including the Home Office.
Suggestions that the security services believed Islamic groups such as Hamas and Hizbollah would not carry out attacks in London because of the potentially disastrous repercussions were dismissed as untrue.
However, it is understood that neither MI5 nor MI6 were aware of any immediate terror threat in the capital, or that an active unit intended to bomb the Israeli embassy. It became clear yesterday how a terrorist had managed to penetrate one of the most sensitive streets in London to plant the Israeli embassy bomb. Guards who control barriers at either end of Kensington Palace Gardens had been given no advice to be more vigilant over recent days.
The Metropolitan Police, and the Crown Estate which employs them, say the barriers are not there for security. Guards have no power to stop anyone; even after the two bombings in the past two days these rules have not changed.
The freeholds to all the buildings on the private street belong to the Crown Estate, which employs private security guards from the Corps of Commissionaires, a non-profit making company which employs personnel who have been in the forces, the fire or services.
Jack Peck, area manager for the Corps, said: 'We always record the registration number, the time, and where the visitors say they are going.' The only security role is to report anything suspicious to the Diplomatic Protection police. 'It is difficult to define what we would pass on. You know if something is not quite right.' The woman who bombed the Israeli embassy was not reported as suspicious. Her number plates were false.
The guards let through unquestioned any car with diplomatic number plates, and allow in any driver who says he or she has come to collect a visa from an embassy. No check is made to see if they went where they said they would.
Leading article, page 17