David Cameron is under growing pressure to beef up measures to combat Islamist extremism in Britain as the hunt for James Foley's killer continues.
The Prime Minister has insisted that authorities are working hard to track those who have come into contact with Islamic State (IS) militants.
But Lord Carlile, former independent reviewer of terrorism legislation for the Government, said the decision to scrap the control order system in favour of more limited terrorism prevention and investigation measures (Tpims) should be revisited.
I do think the Government could make a legislative response to the current problem by reintroducing control orders, or beefed-up Tpims, as they are called, to ensure that people who are identified by solid intelligence as presenting this kind of risk can be placed under controls which can prevent them activating their ideas.
I think that we can demonstrate that, certainly in the last six or seven years of control orders, they were very effective, including a provision that allowed certain people - if a judge agreed, a very senior judge - to be relocated.
Of course, there are no Tpims at all at the moment. The Tpims that were created ran out and the Government decided to have no more, for reasons which I have never understood.
A British family have told ITV News of their devastation after discovering a close relative is fighting with the Islamic State in Iraq.
A French journalist who was held hostage with James Foley in Syria has told ITV News it was "devastating" to see his murder.