Jacko Jackson is a part-time agent for MI-5.
Truthfully, he is a crook. At least, that is what most of the policemen and members of Scotland Yard who have heard of him would likely say. He has no criminal record, other than the time he spent in military prison at the end of his career with the Special Air Squadron for an infraction that is not clearly defined, but since he became a civilian again, he has had numerous run-ins with the law. Nothing ever stuck to him and he is pleased to say he is basically clean but those in the know would wink at the notion that Jackson was on the up-and-up. Especially when he does not have much in the way of visible earnings and he drives a beautiful Ferrari. Exactly what sort of criminal enterprise Jackson might be in, though, was something few could really nail down. Jackson would just grin if ever asked.
William is his legal first name but his time in prison gave him the nickname of "Glasshouse" in honor of the facility that housed him. His more common name, though, is Jacko, earned during his SAS time. It was while serving there for several years that he earned more than the name; he became known as a fairly wild operative who could be counted on to undertake some outlandish assignments and then pull them off. His reputation as an achiever was equaled by his rep as a loose cannon, the latter being not really fair.
Jackson's membership in this collection of spy characters comes not from his seeking such a position but because his help was sought on two occasions by agents of MI-5. The first time it was by a retiring agent named Towler who was up against some powerful people in a case where his friends and his enemies looked a lot alike. With his options running low and needing a strong hand to survive, Towler looked up his old friend Jackson and the two went for a very fun, albeit explosive, trip. Jackson's involvement in the case did not come until well into the second half of the book but his role was crucial to the outcome and when he arrived on the scene, he made an impression.
Having once served in a freelance nature, Jackson is neither surprised nor pleased when he is approached again to help in a governmental matter, this time involving a case which resulted in the death of a police commissioner. Jackson is needed because the official method of investigation got the first man killed and it was hoped that by using someone outside official channels the truth might be achieved. Jackson's numerous outside-the-law enterprises were used as a leverage to get his help but Jackson was intrigued by the adventure nonetheless.
Besides being a good man to have on your side in a fist fight, Jackson is especially skilled with a hand gun, a fact that keeps him alive on several occasions. He is very comfortable with the ladies and he enjoys the respect of a large number of men both in the military and in the underworld.