What to do? I believe in sticking as closely to that past as I can while also remembering I'm creating a fictional world for my readers. Deborah Hale refers to this as "Walking the Historical Tightrope" and each time I panic, I refer back to her words of wisdom. Still, the historian in me continues to read as much as I can on spies from times past. One article by Clive Elmsley, "The Home Office and Its Sources of Information and Investigation 1791-1801," English Historical Review 94 (1979): 532-61) gives me hope -- he mentions that a history professor from St. Andrews University acted for the Home Office during my period. Yippee! Not only that, magistrates and post masters and mistresses also aided the government by monitoring the missives passing through their hands.
Still, in the end, a certain amount of romanticizing does seem to be called for when creating our heroes' occupations. And their heroines. After all, we rarely mention the lack of bathing, oral care, shaving and the other general nastiness of every day life in earlier eras, even for the upper classes.
So -- with what aspects of the past do you take literary license?