Danny Pearson is a part-time agent with British Intelligence.
Exactly what department in that community is not really specified, something that the man who identified himself to Pearson as Howard ("take you pick, Smith, Jones...") would find pleasure in and work to maintain it. The little we are told of him was that he was "one of the good guys" who was "in charge of a very special division of national security. No official titles and very off the books". Pearson is visited by Howard while he was sitting in a jail cell after a fair amount of mayhem in the first recorded adventure and told that should Pearson agree to his offer of occasional work, all the trouble from the things he did that got him put behind bars would go away. "A man with your particular skill set is hard to find. From time to time we may ask you to do something for us. You will, of course, be paid very well for your services and discretion."
To Pearson's credit, looking at the stark reality that the tiny cell and the bars foretold of his future, did not really hesitate at all. He did throw in one condition - "I'm in charge, I do things my way". Howard was quite agreeable.
Prior to his temporary remand in custody and even before the trouble that got him there, brought on because Pearson disapproved of the way a Russian mafiya crime boss was causing trouble for Pearson's uncle, Pearson had just gotten out of a lengthy stint with the elite British SAS, seeing far too much very unpleasant things in the Middle East, especially Afghanistan. It was after one horrific mission to rescue an diplomat and his family from Al Qaeda, said hostages brutally murdered before Pearson's team's arrival, that Pearson decided he had had enough and wanted to come home.
Home was not quite as pleasant as Pearson might have wanted, though. His mother was rapidly nearing the end of her life from a disease that would not let go and the streets and buildings all reminded him of a previous loss, "his own wife and child had been killed a couple of years ago, when a lorry driver crushed their car before driving off, never to be found". Still, it was home and there was no trouble and no fighting and no killing. For a couple of days, at least.
Then Pearson's uncle, who was not quite as law-abiding as Pearson had thought as a child, had a run-in with that rival gang leader and Pearson got involved to help his uncle out and that lead to a fair number of casualties and that lead to jail which, as mentioned above, led to Pearson having a new side gig.
His full-time work would come as the new Director of Operations for Greenwood Security, a private firm that got a good amount of work from providing security work for corporations and organizations but also was always on tap to help the government with an odd request or two. That work will keep Pearson pretty full-up with dangerous assignments and then there will be those occasional requests from Howard. And it seems that Pearson's small cadre of friends are also quite good at getting into scrapes needing Pearson's knack for finding a solution. Pearson will be a busy man.