Aimen Dean, who worked for UK intelligence within AQ for four years (1998-2002), has now written - with two co-authors - a book "Nine Lives: My Time as the West's Top Spy Inside al-Qaeda". His motive to change sides:
Betrayal of the treacherous is loyalty in the eyes of God. I betrayed a bunch of criminals, it’s as simple as that.
Link to publisher:https://oneworld-publications.com/nine-lives.html

In after his defection, following a US media report "outed" him, he did go public with interviews with the BBC in early 2015.
Link:https://www.bbc.co.uk/news/magazine-31700894

As part of the publicity he has now been interviewed in the UK, at least twice and in the USA - with a CNN documentary to come. Link to UK interview on C4 News (8 mins):https://www.channel4.com/news/i-was-...nside-al-qaeda A longer interview on LBC (20 mins) with Maajid Nawaz:https://www.msn.com/en-gb/sport/vide...iew/vi-AAyqlUs
Link to short CNN item:https://edition.cnn.com/2018/05/23/w...spy/index.html