So the British police have had their first big breakthrough in the Islamist terror campaign against London. There was an audible sigh of relief in Scotland Yard at news of yesterday’s capture of one of the prime suspects in the abortive suicide bomb attack of July 21, together with separate arrests of five other suspects, two of them on a train to King’s Cross train station, where 21 people were killed in the subway on July 7. What seems to have been a secret bomb factory has also been found in London.

The dramatic manner of the alleged bomber’s arrest – he was stunned with a Taser gun and arrested in Birmingham – did much to lift Londoners’ spirits, which had been depressed by the failure to catch the four escaped terrorists.

Last week’s shooting of an innocent Brazilian, mistaken for one of the gang, was highly counterproductive, leading many to question the judgment of the Metropolitan Police Commissioner, Sir Ian Blair. The commissioner has an unfortunate reputation for placing political correctness above catching criminals, for which he may now be overcompensating with his crudely applied “shoot-to-kill-to-protect” policy.

The task of finding a needle of Islamist terrorists in a haystack of British Muslims has placed the Metropolitan Police under the unforgiving scrutiny of the international press. Naturally, I turned to Sherlock Holmes. In the 118 years since the great detective made his appearance, very little has changed.

In his very first investigation, “A Study in Scarlet,” Holmes’s assistant and chronicler, Dr. Watson, describes London as “that great cesspool into which all the loungers and idlers of the Empire are irresistibly drained.” Well, Watson may have had in mind former colonials like himself. But his remark applies even more appositely to the self-styled Muslim clerics and professional agitators from former British colonies such as Pakistan, Afghanistan, and Iraq who fetch up in London, live a life of leisure, often at the expense of the British taxpayer, and busy themselves creating networks of Islamist terrorism.

It was Holmes, of course, who provided the definitive critique of Scotland Yard. Time and again, the police, personified by the stubbornly unimaginative Inspector Lestrade, dismiss Holmes’s far-fetched “theories” in favor of “facts,” only to be humiliated by an unforeseen twist – unforeseen except by Holmes. “I am a practical man, Mr. Holmes, and when I have got my evidence I come to my conclusions,” declares Lestrade in “The Adventure of the Norwood Builder.” His conclusions are invariably mistaken.

Holmes does grant Lestrade and his men one virtue. In “The Adventure of the Three Garridebs,” when Holmes thwarts Killer Evans, an American gangster, he remarks of the Yard: “There may be an occasional want of imaginative intuition down there, but they lead the world for thoroughness and method.”

If only that were still true. Incidentally, even when Killer Evans shoots and wounds Watson, Holmes does not shoot back, but merely stuns him with the butt of his pistol. Suicide bombers can’t always be taken alive, but they can sometimes be rendered harmless before they have a chance to be dangerous. It is, of course, vital to apprehend the members of this particular Al Qaeda cell alive, so that they can lead us to their masters.

Once, and once only, does Holmes venture into politics. In “The Adventure of the Bruce-Partington Plans,” he is called upon to recover the strategically vital blueprints of a new submarine that have been stolen from a clerk found dead at Aldgate Underground station – by coincidence, another of the scenes of the July 7 Al Qaeda attack. Once again, Lestrade of the Yard proves to be out of his depth, so Holmes’s brother Mycroft (even more brilliant than Sherlock, occupying an obscure but indispensable office in government) calls in the great private detective. Holmes duly solves the mystery, but only after exposing a grave case of treason within the armed services. The traitor is then used by Holmes to lure the enemy agent back from Paris into the hands of the police.

The lesson of all this for Britain today is that a war of intelligence requires intelligence of the ordinary kind, too. If Sir Ian Blair is another Lestrade, he must be replaced. We need to mobilize the latent mental powers of a nation which, according to Charles Murray’s study of “Human Accomplishment,” outstripped all its European rivals in sheer numbers of creative individuals between 1400 and 1950. No other country, except America, can bring so much knowledge and experience to the war on terror. Now that London is on the front line of that war, we must outwit the Islamists, just as we outwitted the Nazis and the Soviets.

But just as treason was a serious danger in the Cold War – who can forget the spy rings that penetrated to the heart of the British establishment? – so, in a different form, treason has become the most lethal threat to security today. The Muslim minority is now on trial. A poll in yesterday’s Daily Telegraph shows that 57% of Britons agree that Islamist terror threatens the British way of life. Less than half that number have so far made up their minds that Islam is incompatible with Western liberal democracy, but as many again are unsure. The coming weeks and months will decide the issue.

In the aptly titled “Two Cheers for Democracy,” E.M. Forster – part of the same Bloomsbury set as several of the Cambridge spies – notoriously boasted: “If I had to choose between betraying my country and betraying my friend, I hope I should have the guts to betray my country.” Muslims now face the same dilemma. If they follow Forster’s principle, how can Islam ever be accepted in Britain?