This is a hugely interdependent world and hence, potentially, a vulnerable one. The momentum behind this growing interdependence is so strong that it will, mercifully, take more than a terrorist bomb to derail it. But three times in the past century, in 1914, 1929 and 1939, a strong and interdependent world economy has been destroyed by strife. We should remember that if terrorism pushes us towards erecting barriers between different countries and different people More from Hamish McRae. The first I heard was when my neighbour Althea dropped by, at about half nine. "There's been a big explosion at Liverpool Street," she said, so we rushed to switch on BBC News 24 What the broadcasters told us was soothing and plausible. A power surge had caused electrical faults at various points on the underground, notably Edgware Road and Aldgate East, and some stations were being closed There were a few minor injuries.

Some pissed off looking commuters were questioned as they were evacuated from Stratford station, their comments innocuous and innocent of trauma. We accepted what we'd been told, eager, desperate, to believe that the terrorist attack that we'd become used to dreading, hardly noticing the dread any more at the back of our minds, was not coming today. Reassured but not totally convinced, I headed for the gym, where the instructor, Nick, was already alert to the fact that something was up. We watched Sky News with an MTV soundtrack, providing our own running commentary as I pounded and pumped away. At first, we barely questioned that we were watching an unfolding accident.

Certainly, that was the message the police were putting out over the airwaves.Gradually, though, that scenario stopped making sense. If it were true, people would be coming on the telly, telling us not to panic, saying that everything was fine They weren't, so everything wasn't fine. Sky News was so hard up for information that they were appealing for eyewitnesses to send in e-mails. Then, as the television continued to show pictures of London streets peopled only by emergency vehicles, a couple of captions began flashing up. One said that a double decker bus had crashed, with some casualties. The other said there had been an explosion on a bus.Suddenly there were too many biffs and bangs and knocks for this to be coincidental. A rail union and a rail business broke ranks and started hinting to the media that something was amiss.