They now hope that Aine Davis, who is in custody, will unlock the secrets of ISIS fighters in the UK and across Europe.

Detectives believe that one of the 10 Paris attackers contacted former London Tube driver Davis, 30, while he was in Turkey.

Turkish police arrested Davis shortly before the attacks in Paris.

British counter-terror police hope his mobile phone records and other items will lead them to others linked to the global terror network.

Davis was a close friend of butcher Jihadi John, Mohammed Emwazi, who was killed in a US strike in Syria earlier this month.

Davis, from west London, appeared in several ISIS beheading videos and apparently guarded foreign prisoners for Emwazi.

Detectives believe that an ISIS terrorist plotting the Paris attacks called Davis when he was in Istanbul, where he was believed to be gun-running.

Meanwhile, West Midlands police are investigating claims that one of ISIS’s Paris squad made calls to someone in Birmingham.

A US newspaper has claimed that ringleader Abdelhamid Abaaoud, 27, had links to several people of Moroccan heritage in the city.

Abaaoud, 27, was killed five days after the Bataclan massacre, which claimed 89 lives.

West Midlands Police assistant chief constable Marcus Beale said: “There have been a number of recent speculative media reports regarding the attacks in Paris and potential contact with people or places in Birmingham.

“The counter-terrorism unit is working with colleagues and security services to provide support to the French and Belgian investigations and to address any threat to the UK.”

The force would not be drawn on a report that one of the gunmen travelled to Birmingham and London earlier this year.

Scotland Yard counter-terror experts are also examining claims that one of ISIS Paris squad visited London and Kent before the attacks.

It was also confirmed that Eagles Of Death Metal, the US band which survived the attack at the Bataclan theatre, will join U2 on stage in Paris tomorrow,Express reported.

E/S1