Monday's conviction of three young British Muslims has boosted the service after recent setbacks. But concerns remain about the ongoing radicalization of young Muslims.
Having secured the convictions this week of three homegrown terrorists who had plotted to blow transatlantic airliners out of the sky using bombs disguised as drinks, Britain's security service is enjoying its proudest antiterrorism moment in years.
The recent past has included its share of setbacks. Nine Pakistani students suspected of involvement in what Prime Minister Gordon Brown claimed was a "very big plot" were released without charge in April.
But Monday's high-profile convictions of three young British Muslims, following the largest counterterrorism investigation in British history, is being widely praised.
Abdulla Ahmed Ali, Tanvir Hussain, and Assad Sarwar were found guilty of conspiring to bomb several airliners on routes serving Britain, Canada, and the United States. Prosecutors said the men had planned to make explosive devices from the common disinfectant hydrogen peroxide, batteries, and other household goods while in flight.
Their arrests, and those of a number of others in August 2006, radically altered aviation security for millions of travelers by prompting restrictions on liquids.
Paul Cornish, professor of international security at the Chatham House think tank, said the convictions were evidence of a well-run investigation. "I would also suspect that a lot of work is actually still ongoing," he says, "and has yet to be revealed."