Deputy Assistant Commissioner Peter Clarke. head of counter terrorism at Scotland Yard, issued this statement after the convictions of five men who plotted to bomb UK targets.
Mr Clarke said the five were "ruthless"
We are pleased that the overwhelming evidence presented to the court against these men enabled the jury to reach their decision.
This case marked a new stage in our understanding of the threat posed by Al Qaeda to this country.
The investigation showed the links that these men had with Al Qaeda in Pakistan.
Most of them had attended a terrorist training camp in Pakistan in 2003, and were taught how to make explosives; some had been involved in extremism as far back as 2001.
This was not a group of youthful idealists. They were trained, dedicated, ruthless terrorists who were obviously planning to carry out an attack against the British public.
Operation Crevice is a landmark case for a variety of reasons, in particular the scale of the investigation that was needed to gather the evidence to bring these men to justice.
The threat posed by this group of men demanded an unprecedented response from the police and security service. It was imperative that the public were protected from these men and their plans.
At the time it was the largest counter terrorism operation ever seen in the UK. The success was achieved through close co-operation and sharing of intelligence between the UK, the USA, Canada and Pakistan.
It was the first time since 9/11 that we in the UK had seen a group of British men intent on committing mass murder against their fellow citizens.
They were involved in an international conspiracy, and the evidence showed that they would not balk at killing as many people as they could. We heard them praising the attacks in Madrid, saying that there were no such things as innocent victims. They had to be stopped.
There is always a balance to be struck between allowing terrorists to go ahead with their planning, so that we can gather evidence, and making sure the public are safe. We will never gamble with public safety.
In this case we decided to arrest the plotters when we feared that they were getting closer to mounting their attack. We could take no risks.
While under surveillance they were heard discussing possible targets such as shopping centres, nightclubs, trains - all heavily crowded places where the loss of life and destruction could have been massive.
We now know that two of the people who attacked London on 7 July 2005 met with Khyam's group during the Operation Crevice surveillance operation. They were not part of that plot, and at that time were not a threat to public safety.
In every case, and Operation Crevice was no exception, decisions have to be made as to who poses a threat to the public, and how resources should be used.
The decisions made during the investigation have been examined by the Parliamentary Intelligence and Security Committee. Their report was published in May last year.
It is a grave disappointment and a matter of great regret to everyone involved in counter-terrorism that we were not able to prevent the attack on 7 July 2005. What this case and others in the future will show is that we are dealing with a threat posed by interlinked networks of terrorists.
We will continue to do everything within our power, and within the law, to keep the public safe from the threat of terrorism.
Everyone involved in Operation Crevice - police, security service and Crown Prosecution Service, can be proud of their role in helping to stop a terrorist atrocity and gathering and presenting the evidence which has led to these convictions.