I have a character who works for the British Foreign Office in 1811 and needs to be sent to Lisbon as part of the British Embassy. Not knowing much about the intricate workings of international diplomacy, especially of the 18th and early 19th centuries, I'm wondering in what capacity I could have him sent. I need him to be important enough that he would have access to the Foreign Office codes and information about supply ships running from England to the Iberian Peninsula to support Wellington's army, but I certainly don't want him to be too high up in the hierarchy. In other words, I don't want him to be an ambassador or an envoy or anything like that.
Any suggestions, links, search terms, etc. would be most appreciated. Thanks in advance!