Tony Blair is taking the threat of Al-Qa'eda attacks on Britain seriously, writes James Corbett in London Whenever Britain has been at war or involved in conflict its people have held an innate fear of enemy agents operating on native soil. Suspicious eyes have perennially followed unknown faces, and police forces inundated with tip offs about "undesirables" and "outsiders". Sometimes foreign suspects have faced a more arbitrary end. During the Napoleonic Wars, for instance, a shipwrecked monkey was hanged in the north-eastern town of Hartlepool because its residents -- not knowing what a Frenchman looked like -- thought it to be a spy. More recently, England's sizable Irish community faced widespread harassment during the IRA's lengthy mainland bombing campaign. It was also an era that saw many purposely avoid the capital and provincial shopping malls -- two of the terrorists' favourite targets. Facing a mix of genuine trepidation, civic duty and, sometimes, plain distrust of strangers, any would-be conspirator will have operated in a sea of wariness and fear. Until now it would seem. Perhaps because Britain is facing an unseen enemy in Al- Qa'eda or maybe because the country is yet to be directly attacked by its forces, Osama Bin Laden has somehow failed to inspire previously held levels of fear and paranoia in Britons. Even Tony Blair's sombre warning last week that Britain faced the threat of chemical or suicide attacks in the run-up to Christmas did little to excite a sense of panic in a country that has been more preoccupied in recent weeks by a string of tabloid sex scandals, alternatively involving TV stars and the royal family. Blair's comments came in the same week that the Home Office published a document that warned of potential dirty bomb or poison gas attacks and suggested that terrorists may target boats or trains rather than aeroplanes. More ominously, 24 hours after Blair's comments, Osama Bin Laden's latest warning to Bush's "criminal gang" -- in which Britain was specifically named -- was broadcast, threatening that "You will be killed, just as you kill." But again the British public waking to headlines filled with further threats and warnings were more likely to turn the pages of their newspapers to the latest revelations in the ongoing royal drama. Even those living and working near the most obvious targets for an attack have given little thought to such a possibility. Stephen Tudhope, a researcher in the Houses of Parliament, typified the mood, by giving an indifferent shrug when I asked him if the latest reports gave him renewed cause for concern. One suggestion was that terrorists may target a passenger ferry sailing into Britain. Even with increased police presence a lorry bomb would be devastating and relatively simple. Passengers making the short journey from France are seldom asked for identification and less common still are vehicle checks. But again, none of this seemed to bother the hoards of passengers last week making their way across the English Channel to France to stock up on tax free cigarettes and alcohol in time for Christmas. Of those who have paid greater heed to Blair's caution, many have criticised him, suggesting that he has exaggerated the threat and is panic-mongering in order to gain support for draconian surveillance and anti- terrorism laws he has been trying to pass since 11 September, or even for a ballistic missile defence system that has been mooted by his Defence Secretary Geoff Hoon. More likely, Blair is trying to cover his own back in the conceivable, though unlikely, event of an Al- Qa'eda attack. Having seen the gauntlet of criticism George Bush faced after not passing on similar warnings last year, it is probably a shrewd move. All things being equal, the British public would do well not to be so blasé about the prospects of an attack. Osama Bin Laden's (albeit increasingly infrequent) broadcasts have usually served as a prelude to an Al- Qa'eda attack, the last of which came ten days before the Bali bombings in October. Moreover, the British security forces who provided Blair with his information are possibly the most qualified and knowledgeable in the world, having benefited from four decades of counter-terrorism in Northern Ireland. Unlike their American counterparts, who have perpetually "cried wolf" over the past year, this is amongst their first major warnings. When MI5 or MI6 speak out people should listen. Professor Paul Wilkinson of the Centre for Terrorism Studies at St Andrews University said it was a "possibility" that the threat did exist and that the original Home Office warning was not inaccurate. "We know the American intelligence authorities are quite convinced that Al-Qa'eda have been examining the possibility of using a dirty bomb in the United States and of course we have known for some time that Al-Qa'eda's been seriously pursuing chemical and biological weapons," he told BBC Radio 4's Today programme. "So it's sensible to look at the worst case and also to take into account that the more traditional forms of terrorism are still a danger. We could have for example suicide hijacking, we could have attacks on particular areas, particular buildings with truck bombs." He added that it was "wise" for the Home Office to let the public know of the whole spectrum of threats. Neither Blair nor the Home Office would specify any particular target. In all likelihood they do not know, and if they did, they would not make it public through fear of causing hysteria. Nevertheless the rise in armed police (the vast majority of British police officers do not carry guns) around Parliament, prominent embassies, ports and airports has been noticeable over the last ten days. As has so frequently happened in his crusade against global terrorism, Tony Blair faces a difficult balancing act. On the one hand he has a duty to protect and warn his public of any perceptible dangers. On the other, it is crucial that he does not overplay remote threats. "If the public responds by staying at home, the terrorists have won," one government source said. "Yet if a terrorist attack happens, then the public asks 'why didn't you warn us?'"