BBC reporter, Peter Taylor and an assistant, have a hour long 'Panorama' documentary on:
From highly organised cells like the one that killed 130 people in Paris, to lone attackers within our own communities, Panorama reveals how the so-called Islamic State's terror network has been operating secretly in Europe, and Western intelligence agencies' battle to stop it.
Link:http://www.bbc.co.uk/iplayer/episode...terror-attacks

It aapeared on TV here 23rd March 2016, it clearly relies on a number of "leaks", notably from the French, supplemented by a number of interviews and especially of an ISIS suspect in French custody.