The killing of a young Brazilian by police marksmen on London’s Underground this week could be taken as a sign of how jittery the British have become about the terrorist menace. It certainly highlights the immense difficulties faced by law enforcers in every country where the scourge of the suicide bomber has raised its wicked head.

The 27-year-old Jean Charles de Menezes appears to have been in the wrong place at the wrong time. British police have been reticent about the precise details that led up to the Brazilian electrician’s death but a few facts can already be pieced together. The victim lived in Tulse Hill, close to premises that anti-terrorist police had under observation. He appears to have visited those premises and then gone to Stockwell underground station. When challenged to stop, the Brazilian allegedly ran and was shot in the head and killed. The authorities are suggesting that De Menezes’ visa may have expired, a statement denied by his family who maintain he was in the UK legally. If the British are however right, it could explain why the young man apparently sought to flee. A refusal to stop would have triggered the rules of engagement given police firearms specialists dealing with suspects who may have bombs — which is to kill rather than disable them.

The British are clearly deeply embarrassed and extremely sorry for this awful mistake, no doubt the more so because the Brazilian foreign minister was by coincidence on a visit to London. However British Muslims are even more concerned. Already finding themselves the object of suspicion as they go about their daily lives, they are now having to grasp the appalling possibility that if they too have the misfortune to be in the wrong place at the wrong time and make a split-second, panicky error of judgment when ordered to stop by armed British policemen, they could also be shot in the head.

The British are wrestling with a terrible dilemma but since the 7/7 London bombings the pendulum has begun to swing away from resolute and tolerant multiculturalism. In the wake of the first attacks, unchallenged statements were made about the failings of the British Muslim community, by some politicians which a week before would have opened them to angry criticism in the liberal press. Leading Muslim figures, shocked and horrified at what had been done by some of their co-religionists, justified this shift by their own admissions of shame and anger.

There is a danger here that like most pendulums, this reaction to the entire Muslim community could swing too far and give cover to the racist bigots that exist in all societies. Most importantly, the British must realize that the slaying of an innocent man by anti-terror police was not just a tragedy, it was also a victory for the very terrorists they are trying to defeat because it undermines the fabric of a society that prided itself on tolerance and moderation.