THE reputation of the British security services has been seriously undermined by high profile errors during the war on terror, most notably the shooting of innocent Brazilian, Jean Charles de Menezes, and the Forest Gate fiasco.

But the events of yesterday underline the scale and the importance of the task they are facing.

We all know that the threat is there but it is only brought into sharp focus when details emerge of the kind of terrifying plot which was exposed yesterday.

With security experts believing that up to ten aircraft were in line to be blown out of the sky, a disaster of chilling proportions appears to have been averted.

It is a frightening time but we should all take comfort from the knowledge that those planning this latest atrocity had been under surveillance for months and were stopped from succeeding when it became clear that the attacks were imminent.

We should also acknowledge the role that the law-abiding Muslims have played in the intelligence process and understand that it is only a tiny minority of extremists who seek to commit mass murder.

It is, of course, right that the security services are called to account when mistakes happen. There must be investigations and lessons learned from their failures.

But it is also right that we acknowledge the size and complexity of their challenge and applaud their life-saving successes.