David Cameron faced calls for changes to the law in an effort to combat the threat of Islamist extremism in Britain following the murder of American journalist James Foley.
Intelligence agencies on both sides of the Atlantic are working to identify the jihadist believed to have carried out the brutal killing, with e xpert analysts sifting through the gruesome footage for clues amid suggestions that the Islamic State (IS) extremist is from London.
Ministers, the police and MI5 are concerned about the threat from British nationals who have travelled to Syria and Iraq to fight for IS returning to the UK to carry on their jihad.
Hundreds of Britons are believed to have travelled to the region, and “significant numbers” are believed to have been involved in “terrible crimes” and “probably in the commission of atrocities” according to Foreign Secretary Philip Hammond.
The Prime Minister, who has resumed his family holiday in Cornwall, spoke about the threat to the UK when he returned to Downing Street following the release of the video of Mr Foley’s execution.
He said “far too many” Britons had travelled out there and promised to “redouble” efforts to stop them going.
Former Middle East minister Alistair Burt said the Government should revisit the decision to scrap control orders in favour of Theresa May’s Terrorism Prevention and Investigation Measures (Tpims).
He told The Guardian: “If the authorities believe someone to be dangerous – what sort of monitoring is possible of that individual?
“That raises the issue of control orders coming back onto the agenda again. It is time to revisit control orders. These were cancelled when we came into office. But circumstances have changed.”
Tory MP Julian Lewis, a member of the Intelligence and Security Committee, said the Government should do more to tackle the promotion of extremist ideology.
He told the newspaper: “If we try to be neutral between the arsonist and the fire brigade then we run into problems.
“We were not neutral in this country between Nazi doctrine and democracy or between Communist doctrine and democracy.
“We should not be neutral between Islamist totalitarianism and democracy.”
The jihadist in the execution video is reported to be “John”, the ringleader of a trio of UK-born extremists responsible for guarding Western hostages and nicknamed after members of The Beatles, with the two others dubbed Paul and Ringo according to the BBC.
In the video of the murder of Mr Foley, US president Barack Obama was warned that the life of American hostage Steven Sotloff hinged on his “next decision”.
But the US continued to launch air attacks on IS forces to shore up Kurdish and Iraqi efforts to hold the strategically important Mosul Dam.
British spies are heavily involved in efforts to identify Mr Foley’s killer and his group of extremists, with the Cheltenham-based eavesdropping agency GCHQ playing a vital role in intercepting any electronic communications between jihadists in Syria and Iraq.
The British agencies – MI5, MI6 and GCHQ – were also working with American and European counterparts and receiving reports from agents on the ground to try and build a more complete picture of the scenario in Iraq and Syria.
However, much of the ongoing work will not deviate from everyday business as the hundreds of Britons who have travelled overseas to take up jihad have for some time been of central concern to the security services.
Downing Street said the Prime Minister would continue to receive regular updates and briefings on the situation while he was in Cornwall.
A No 10 spokesman said: “The Prime Minister has returned to Cornwall after holding meetings in Downing Street yesterday on Iraq and Syria, following the murder of James Foley. He remains in close contact with his team and will be kept fully up to date.”
Dr Andrew Mumford, a lecturer in politics and international relations at Nottingham University, said intelligence services faced a “big task” in trying to identify the murderer, and would be combing through people known to have links with Britons who have travelled to fight in Syria.
But he warned the agencies could face problems if the killer had travelled to the region “under the radar” with “no background in terrorism or any other criminal activities”.
On the role of “The Beatles” in guarding kidnapped Westerners, he said: “A picture is emerging that IS is now explicitly using Western jihadists to take control and look after Western hostages. That is an important and interesting development.”