Oliver Wade is an agent of the Crown.
More specifically, he is an unofficial operative pressed into service of Lord Robert Cecil, 1st Earl of Salisbury and Secretary of State to Queen Elizabeth.
As the both loved and feared elderly monarch was obviously nearing the end of her life and reign, her chosen successor, James I, had a considerable number of detractors. Many in various positions of power wanted a Catholic to take charge again like the preceeding Queen Mary while as many, if not more, wanted things to stay as they had been for nearly a half century. Working on behalf of his current soveriegn, and many said moreso on his own behalf, her trusted servant Cecil worked diligently to root out the former to ensure a peaceful transition of power.
One of his tools was young Wade, to that man's dismay. Wade had been a soldier for a time, like his father William still was. When we first meet him he is an actor by stated trade and apparently a wooer of women by avocation. It was for that last that Wade is thrown into jail as he was doing the seduction a bit too out in the openness and lewdness was a crime. It was while he sat in his cell that Cecil approached him with a chance to get out of trouble and do something noble for the Crown. Wade probably could not care a whit about the last but the first definitely interested him.
So Wade, who had no training as a spy but who had considerable abilities at listening, observing, and remembering, got a new job mingling with people and ferreting out those who would be active in their desires for a regime change.