Nora Kelly is an agent with British Intelligence.
This version of the governmental clandestine bureau really has no name as it is very much a top-secret operation working directly for the Queen of England, in this case Queen Victoria as it takes place during her reign. The department has a name which I will get to later but that name is known to just a handful of people outside the group. The team is run by the very prestigious and respected Duke of Cambridge, a close friend and confidant to Her Majesty.
Working as his best field handler is Alfred Covington, a handsome and very dignified individual, if a bit too easily made to blush by the frankness and openness of Kelly and her close friend. It is Covington who recognized the potential in Kelly and recommended her recruitment and it was he who would set up her training once she was offered the position and accepted it.
Kelly will not become a "standard" operative, however. She will willingly become one of the special agents who allowed herself to be turn into a vampire to acquire the powers and skill she would need to work for the Duke's organization. Her agreement to make this drastic change would come from the bleakness of her life up to that point. This young woman with the long fiery red hair and gorgeous features was likely in her late teens and for the past several had earned her living as a prostitute in the Limehouse District of London. And when she was not pleasuring men with her body, she would most often be found in one of the opium houses, stoned out of her mind to forget what her life was really like.
As mentioned, Covington has spotted in the destitute Kelly the potential to become a vampire who would then work for the government (what that potential was is best read for yourself). Interestingly, the fact that Covington would be the one to set up her transition as he had several others before would fly in conflict with the fact that he was one of the world's most feared vampire-hunters!
Now to the mention promised about the unofficial name for the nascent group of vampiric operatives. For reasons I could not quite fathom, these newly created vampires would be known as mortal/immortal beings or MI's. We also learn that Her Majesty had authorized the Duke to have up to six vampires as field agents. As a result, the group would refer to themselves as MI-6.