A bomb apparently planted by the Irish Republican Army exploded Friday in the visitors' gallery at the London Stock Exchange, but there were no casualties because the building had been evacuated after a telephoned warning.
It was the first such warning since the start of what appears to be a summer bombing campaign against political and financial targets in London.
About 30 minutes before the blast at 8:49 a.m., a man who said he was a member of the IRA told a British news service that a bomb had been placed at the exchange and was about to explode.
Police officials said that if there had been no warning Friday, the human toll would have been very high.
"There would have been injuries and probably fatalities among the people on the trading floor," Police Cmdr. Hugh Moore said.
He said the warning, which allowed the police to evacuate about 300 employees, did not detract from the gravity of the incident.
"We had only half an hour to reach the scene, evacuate the building and clear the surrounding streets," he said. "If we had been a few minutes later getting there, it would have been too late. These devices are unpredictable, and you cannot guarantee when they'll go off."
Prime Minister Margaret Thatcher said she was appalled by Friday's attack but relieved that there had been no casualties.
Damage to the exchange building was extensive, however. Cmdr. George Churchill-Coleman, head of Scotland Yard's anti-terrorist branch, said the bomb blew a 20-by-7-foot hole in the building's facade, destroyed most of the visitors' gallery and littered the street outside with rubble. He said the bomb appeared to have been placed in the visitors' gallery men's room, possibly during the night.
The explosion had little impact on stock trading, which is carried out largely by computer at brokerage houses elsewhere. The volume of business conducted on the trading floor has declined to the point that the visitors' gallery is scheduled to be closed.
Public reaction was generally light-hearted.
"A computer crash would have hit London's financial markets far harder than today's explosion," the Press Assn., Britain's domestic news agency, quoted one broker as saying.
Outside the exchange building, many of the evacuated brokers continued to conduct business by means of cellular telephones. There was a brief, 10-point rally in share prices, which the Press Assn. attributed to "the British spirit of refusing to be intimidated."
It was the police and intelligence services that appeared to be the most concerned about the explosion. One source said that because the bomb was designed to cause disruption rather than bloodshed, it tended to support fears that the IRA is returning to the terrorist tactics of the 1970s.
At a late hour Friday there had been no formal IRA claim of responsibility for the bomb, but the man who made the warning telephone call reportedly used a code word, known only to militants and the police, that is used to distinguish warnings from hoax calls.
"This is the IRA," he told the news agency Reuters. "The bomb is due to go off in half an hour at the Stock Exchange. Clear the building."
If the IRA was involved, it was their first such move since last month's bombing of the Carlton Club, a popular haunt of members of the ruling Conservative Party.
Some observers noted that Friday's bombing occurred precisely eight years after two IRA bombs exploded in London's Hyde Park as cavalry troops rode past, killing 11 soldiers and injuring 53 others.
(Southland Edition) IRA BOMBING WAVE
A chronology of attacks blamed on the Irish Republican Army since August, 1988, when the current wave of assaults began: August 1988: IRA renews mainland bombing campaign after 4-year lull, blowing up an London army barracks. One killed, 9 wounded. September 1989: Bomb at Royal Marines' music school in Deal, southeast England, kills 11, wounds 22. Feb. 20 1990: Two soldiers wounded when car bomb rips through van near army recruitment center in Leicester, central England. Feb. 24: Parcel bomb explodes at army careers office in northern English town of Halifax. No casualties. May 14: Seven wounded by blast at Army Educational Service headquarters in London suburb of Eltham. May 16: One soldier killed and another wounded by car bomb in Wembley, north London. June 1: Soldier shot dead and another wounded at train station in Lichfield, central England. June 9: Explosion wounds 17 civilians at party in military building in the City of London financial district. June 12: Blast damages country mansion of Lord McAlpine, an associate of British Prime Minister Margaret Thatcher. No one hurt. June 21: Bomb hidden in rucksack explodes outside Royal Air Force base in north London. No casualties. June 25: Bomb wrecks London's Carlton Club, popular haunt of members of ruling Conservative Party, wounding four people. Source: Reuters