Growing up in London -- or anywhere in Britain -- in the 70s and 80s bomb scares were a fact of life. For every genuine terrorist bomb planted there were probably half a dozen or more false alarms, and it became comparatively commonplace to see police cars screaming to a halt outside a tube station or department store and quickly clearing the surrounding area of passers-by.

As a student I would work in the Oxford Street/Regent Street department stores over Christmas and the New Year sales to earn extra cash, and there was a special coded message which would be played over the shop's tannoy to alert the staff that a suspicious phone call had been received. Over the three-week period that I worked there we only had about two evacuations so it was fairly quiet compared with some other years.

What I didn't realise at the time is how much you take being in a state of siege for granted. It's deeply ingrained in my brain that if I see an unattended bag or briefcase anywhere in London I don't think "oops, somebody has forgotten their luggage", but rather I think "better call the police". What I found even more disturbing was just how quickly I found myself falling back into that mode of thinking when the IRA ceasefire broke with the bomb at South Quay in docklands -- it literally took just a few hours for everyone to re-adopt a siege mentality.

Despite all this, it's worth pointing out that although bomb scares (or security alerts as they're now called) happen with depresssing regularity, there haven't been any major terrorist bombs in London for nearly five years, and your chances of actually being injured by such an occurrence are probably roughly on a par with winning the lottery two weeks in a row. It always struck me as odd during the 1980s that American tourists were worried about coming to London, when their own home town may well have had more murders in a year than the whole of the United Kingdom. It's annoying that we don't have bins on the tube though.