I had been reading they've been working on this.
There have been apparently about 500 British Muslims fighting for ISIS/etc, many more than in the British Armed forces.
Britain Close to Identifying Suspect in Journalist's Beheading
Ambassador to U.S. Says 'We Are Close' Via Voice Technology and Other Information
By ADAM ENTOUS - WSJ
Aug. 24, 2014 - 10:10 a.m. ET
WASHINGTON—Britain is close to identifying a suspect who is seen in an Islamic State video beheading a U.S. journalist who had been held captive by the group in Syria, Britain's ambassador to the U.S. said Sunday.
Ambassador Peter Westmacott declined to confirm British news reports naming the suspect in the video but told CNN that "we are close" to doing so.
He said the identification was made possible through the use of sophisticated voice identification technologies and other information. The suspect in the video has what appears to be a British accent.
James Foley, the U.S. journalist who was beheaded in the grisly video released last week, is one of several Americans held by the group known as the Islamic State, or ISIS, in Syria, U.S. officials say.
"Of course, the problem goes beyond one horrendous criminal," the ambassador said. "We've got more people than we would like. People think that maybe as many as 500 British subjects have gone to Syria and Iraq for this cause of Jihad."