How many terror plots have been foiled?
The police say that since July last year four alleged plots have been stopped or disrupted. Three of these will result in trials where the allegations include conspiracies to commit murder, to cause explosions, to mount attacks through the use of poisons, and making plans for terrorist attacks. Full details cannot be given because of risk of prejudicing the trials.
In total there are 60 people currently awaiting trial in the UK for suspected terrorist-related offences. The Metropolitan Police's anti-terrorist branch says it is currently involved in around 70 investigations in Britain and abroad. A more disturbing question, however, is not how many plots have the police and MI5 stopped, but how many terrorist plans are they unaware of.
Why do so few of the people arrested on suspicion of terrorism end up being charged?
In the Metropolitan Police area alone there were 295 arrests under the Terrorism Act in the 15 months up to the end of March this year. These resulted in 33 people being charged with terrorist offences, and a further 28 with criminal offences. About 200 were released with no action. Part of the reason for the relatively low number of terrorism charges is that in many cases the police and MI5 are trying to disrupt suspected terrorist activity. That means they may charge suspects with a criminal offence, such as fraud, or even arrest them to try and scare them off.
There is also the problem of judging when to act. Because the stakes are so high - do you wait until a terrorist cell has built a bomb and is about to detonate it before you strike - the police and MI5 intervene at an earlier stage of an alleged plot than they would in a criminal case. This can give rise to mistakes, particularly where wrong information is given. The raid last month at Forest Gate in east London when an Asian man was shot is a good example. The operation ended in controversy and failure after the injured man and his brother were both released without charge. The police arrested them because an informer had - wrongly as it turned out - told them that there was a chemical bomb in their house. The anti-terrorist branch decided to take action before they could confirm the tip-off because they were fearful that the alleged device might be detonated or moved.
How has MI5 responded to last year's attacks?
The Security Service is in the middle of a huge recruitment drive with numbers of officers having grown from just under 2,000 in 2001 to about 2,500 today, and due to rise to 3,500 in 2008. It has set up an operation code-named Rich Picture in which it is trying to identify people who are being groomed for terrorism.
MI5 knows of more than 1,200 "primary investigative targets" - individuals it believes are intent on carrying out an attack. The Security Service has been credited with greatly improving the intelligence flow on al-Qa'ida terrorists in the UK and for uncovering a number of plots.
But the intelligence agency's reputation has been damaged by a series of disclosures about its knowledge of two of the July 7 suicide bombers prior to the attacks last year.
The two men, Mohammad Sidique Khan and Shahzad Tanweer, were dismissed as peripheral figures who posed no terrorist threat. The agency has also come under criticism for failing to identify the huge threat posed by British-born Islamists.
Do the police have the support of Britain's Muslim community?
The overwhelming majority of Britain's 1.6 million Muslims are opposed to the aims of al-Qa'ida and support counter-terrorism activity in the UK. But community leaders have criticised police stop-and-search actions which are increasingly targeting Asian people.
The latest Home Office figures show that Asians were twice as likely to be searched as white people. Overall there was a 14 per cent year-on-year rise in incidents of stop-and-search to reach 838,700 in 2004-05.
Surveys have shown that from 5 to 7 per cent of British Muslims believe the July 7 bombings were justified.
It is this small, but significant group of radicalised Islamists that the authorities are investigating. The police and Government are making tremendous efforts to win over the support of the Muslim community because they realise that without their help they have no chance of stopping the handful of violent extremists that live among them.
Is another terrorist attack inevitable?
The police and MI5 have only recently begun to understand the huge scale of the problem.
It is incredibly hard to identify individuals - many of whom have no history of violence - in a community where the police and intelligence agents have relatively few contacts. Also it is almost impossible to guard against someone prepared to carry out a suicide attack.
Details of how to make bombs from cheap, readily available ingredients are easy to obtain from the internet. So far through a mixture of luck and skill since the July 7 attacks none of the terrorist plots have been successful. But the authorities cannot possibly know about every conspiracy.
So is there hope for the future?
Every day the police and intelligence agencies are getting better at detecting al-Qa'ida plotters in the UK. Their resources, skills and knowledge are growing. But ultimately the best hope of preventing future attacks lies within the Muslim communities themselves.
Closer relationships and a wide network of contacts needs to be established between the communities and the authorities. At the same time the underlying causes for why a tiny number of Muslim men are prepared to turn on their family, friends and fellow citizens need to be addressed.
Are the police succeeding?
* There have been no further attacks in the past year and more than 60 alleged terrorists are facing trial.
* Record numbers of MI5 and police counter-terrorism officers are working on combating the threat from terrorism in the UK.
* Police are gaining a greater understanding of how Islamists are attempting to groom future terrorists.
* Police and intelligence agencies admit there must be a significant number of plots they do not know about.
* Relations with parts of the Muslim community are being damaged by heavy-handed policing.
* Information and materials to build chemical and conventional bombs are easily available for a few hundred pounds.Reuse content