India Black is an agent for the British Prime Minister.
Not all the time. And not willingly at the beginning. And not officially - definitely not officially. The Prime Minister, Benjamin Disraeli, in London of the 1870s, has enough trouble with a very vocal press and his arch-rival Gladstone, all clamoring for him to be thrown from office because they do not like his politics or his decisions or his manner of dress. If it became known that a person of Black's profession was working for him, it would not go well.
When not performing a job for the PM, Black sits at her place of work, the Lotus House, running the show as she has since founding the establishment several years before. Black is a madam. The Lotus House is a brothel.
She would be earnest in her protests that her place is respectable (-ish) and her girls are clean and decent (-ish). She sells a service that lots and lots of men obviously pay good money for and for the most part the peelers (police) have not come knocking on the door but it is a house of ill repute and totally against the law so running it is a criminal act. She knows this and acts accordingly but she is not ashamed of her chosen line of work and she takes pride in her accomplishments. It just would not go well for the Prime Minister if her connection became known. And business would suffer as well.
Still, running the House does get tedious at times. Customers are always trying to get discounts and freebies. The girls are persistently lazy and catty and would rather hit the sauce than do the laundry. Her cook and housemaid is a woman more prone to guzzling the cooking sherry than using it in a meal. And her friend and biggest rival down the street is another woman who constantly tries to seduce Black or steal her best girls.
Which is partly why when an unfortunate incident took place in her House at the beginning of the series and the dominoes fell such that she was pressured into helping a man named French in a wild and dangerous escapade, she was miffed about it and when it was over, she found she missed the excitement. And that is why she is not at all too unhappy, despite her protests to the contrary, when a gentleman knocking at the door is someone asking for her help, not her pleasures.