Mick Hartley

From this Guardian article:

Both men envisaged being “martyred”, but neither reckoned with the prospect that a man they believed to be a crucial player in their plot could be a counter-terrorism undercover operative (UCO). Because of the courage of the UCO, known as “Farouk”, Saadaoui was captured in the final stages of preparation in a hotel car park, while Hussein was arrested at the shop where he worked.

A prosecution source said of Saadaoui, the prime mover: “This was a man who was quite prepared to go out and kill children and leave his own in the process.” They added: “At one point he says: ‘You know, if we have an AK-47 left over, I will leave it for my son – so he can do what I do when he grows up.’”