A group of terror suspects, branded by officials as a genuine threat to national security, are now free of tough controls designed to prevent them engaging in terrorist activity.
From today, seven of the eight suspects on the UK Government's Terrorism Prevention and Investigation Measures (TPIMs) are now no longer subject to any restrictions.
Terrorism experts have told Sky News that the police and security services would now have to implement costly contingency plans to ensure the suspects were still closely monitored.
The TPIMs programme was introduced by the current Government in late 2011 to replace the much criticised Control Orders regime which allowed the state to place tough restrictions on a small number of terrorist suspects who the authorities were unable to put before the courts.
The TPIMs measures include the wearing of GPS tags, tough controls on the use of phones and computers and restrictions on the people a suspect is allowed to associate with.
But in an attempt to address the widespread criticism and legal challenges the previous Control Orders regime received, the Government set a maximum two-year limit on TPIMs orders.
Seven of the eight TPIMs suspects have now reached that two-year mark and are now free to mix with whoever they want and travel freely without restrictions.
Raffaello Pantucci, a terrorism expert at the Royal United Services Institute, said TPIMS were never a permanent fix for what is a complex issue.
"The problem with TPIMs is that they were always a temporary solution. The underlying problem of what to do with individuals who are clearly of concern to the security services but have not crossed the criminal threshold, how to address these sorts of people, was never really fundamentally addressed."
The former TPIMs suspects, now free of their restrictions, cannot be named for legal reasons, but some were described just months ago as being a genuine threat to the public.
They include 'CD' who the authorities have said is "determined to carry out a Mumbai-style attack in Britain".
He attended a terror training camp in Cumbria in 2004 with four of the five men who went on to launch a failed suicide-bombing attack on the London transport network two weeks after the 7/7 bombings.
Security sources say he repeatedly tried to buy guns for a suspected plot to carry out a mass-casualty attack in the UK.
Another suspect, 'CF,' underwent terror training in Somalia and was caught in the Olympic Park five times in the months leading up to the 2012 games.
Although he never faced trial, 'AM' was described by the authorities as a key player in the foiled plot to blow up transatlantic airliners using liquid bombs.
Imposing restrictions on those who have never been convicted of a crime has always been controversial and both Control Orders and now TPIMs have been criticised by human-rights groups.
Cerie Bulivant was the subject of an anti-terrorism Control Order for two years. His movements were strictly monitored and his access to people and technology were severely restricted.
At one point he absconded before later turning himself in. After a long battle through the courts, he was eventually cleared of all involvement in terrorist activity.
He told Sky News: "Terror control measures do not work and risk further alienating people."
Under his Control Order, he said: "I felt like you have a sword hanging over your throat. Any slip or misdemeanour on any number of conditions could lead to you being in prison for five years; all on the basis of what is fundamentally secret evidence and secret courts."
The Government believes the TPIMs programme has been "effective in reducing the national security risk posed by a number of individuals".
Security minister James Brokenshire said: "It is not possible to discuss individual cases, but the police and security services have been working for some time to put tailored plans in place to manage the risk posed by these individuals once their TPIM restrictions are removed.
"These plans, which are similar to those put in place for the release of prisoners who have served their sentences, are kept under constant review."
Some experts estimate it could cost up to £20m to keep the former TPIMs suspects under effective surveillance.
Former security minister Baroness Neville-Jones said that whatever the cost, they would be monitored.
"Society does have to have protection against people who have represented and may continue to represent a real threat to the community.
"This is a very mild way of doing it because people are having their freedoms restored but on the basis that there is an ability on the part of society to continue to ensure for themselves that actually that freedom isn't being abused."
But the authorities acknowledge no surveillance system is full-proof. Even under the Control Order and TPIM regimes, several suspects managed to escape.
Late last year, Mohammed Ahmed Mohammed absconded from his TPIM order after leaving a west London mosque wearing a Burkha. Three months on, he is still on the run.
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