In Stratford, east London, last week investigators wanted to speak to NHS doctor Shajul Islam, 28, and a second man, Jubayer Chowdhury, 24, amid claims they may hold the key to identifying the jihadi who beheaded US journalist James Foley.
“The city has been a breeding ground for Islamist extremism since preachers including Abu Qatada and Abu Hamza made London their base”
Both were charged with kidnapping Brit journalist John Cantile in 2012, only to be released after the trial collapsed when Mr Cantile was unable to give evidence.
Shajul’s younger brother Razul Islam, 21, is on a list of suspected British jihadists whom the security services are comparing with the footage of Mr Foley’s killer.
The east of the city, dubbed an “Islamic State” recently after terror sympathisers raised an IS flag at the entrance to a council estate in Poplar, is also home to Britishborn hate preachers including Walthamstow-based Anjem Choudary, 47, and Abu Izzadeen, 39, from nearby Leyton.
In west London, Abdel-Majed Abdel Bary, 23, a former rapper from Maida Vale and son of al-Qaida terror suspect Adel Abdul Bary, 53, went to Syria last year and later tweeted a picture of himself holding up a severed head.
Aine Davis, 30, from Hammersmith, west London, is a former drugs dealer who converted to Islam and flew to Syria to wage jihad. He is still fighting for IS.
Both men hail from districts close to the former home of notorious terror preacher Abu Hamza, who is now awaiting sentence in a US jail for plotting to set up a terror training camp.
The hook-handed preacher, 56, lived in a £1.25million council house in Shepherd’s Bush while sending scores of men to wage jihad across the Islamic world from his base at the Finsbury Park mosque in north London.
And earlier this month Amal el-Wahabi – wife of Aine Davis – from Portobello Road in west London, became the first British woman to be convicted of terror offences since the Syrian conflict began.
The former street criminal attended the Brixton mosque as did shoebomber Richard Reid, 41, and al-Qaida plotter Zacarias Moussaoui known as the 20th 9/11 hijacker.
Muslim convert Khadijah Dare, 22, a female jihadi in Syria, is from Lewisham, south-east London.
The former film and media studies student has vowed to become the first British woman to kill a US soldier.
Akram and Mohamed Sebah, killed in Syria earlier this year, are from Holloway, north London.
And Omar Bakri Mohammed, 56, became known as the Tottenham Ayatollah during his heyday running the outlawed al-Muhajiroun terror collective from north London up until 2006 when he left the UK.