What was interesting about Mary-Anne was that it was "socially acceptable" to be a prince's mistress--but not to do the things she did while she was in that position!
Mary Anne married young, to a stonemason--who turned out to be a drunk and a ne'er-do-well. She left him, and set out to seek her own fortune, finding out soon enough that her wit and her beauty was going to be her fortune. She had a few lucrative liaisons, but drew attention to herself was "introduced" to the Duke of York (second son to George III), after which time she swiftly became his mistress.
However, running a royal household--even a royal mistress's household takes a great deal of money, and the Duke's promised allowance was not regular in its arrival. Mary struggled to keep herself in the style to which the Duke would expect, and she knew better than to constantly ask him for money personally. She therefore devised a method of making extra money on the side--and this led to her downfall--for she would take money for commissions, military, clerical, and civil. (the Regency equivalent of our modern day Cash for Honours scandal) and was eventually denounced. The Duke had to resign as Commander in Chief (although he was later exonerated and reinstated) but clever Mrs Clarke was sentenced to nine months in prison.
She did receive a pension from the Duke, however, as a surety against her publishing his letters... That didn't stop her from publishing other things though, including her memoirs.
After the scandal broke her and made her an outcast, she wrote and published "The Rival Princes" which set down her side of the whole affair to even more shock for the population.
"From the justice I owe to my own character and feelings, and the respect I feel for the good opinion of the public, this work derives its existence, which I hope will merit its approbation of those respectable persons who must feel pleased with a complete exposure of those political Impostors, who, under a mask of public virtue, have aimed at nothing but the subversion of that constitutional fabric, which has for ages afforded more freedom to the human character than any other nation in the entire Universe!"The soldiers are saying, "What shall we play next, Jack? 'The Duke of York's March'?" and the other replies "No, let's play, 'She's Off With Another'."
Mary is saying, "Now gentlemen you'd better be quick. I have a few bargains to dissolve of as the partnership is dissolving," and she holds a list labelled, "List of prices at Clark & Co's Warehouse."
The fiddle player is saying, "If you want de commission you must owe me de note, den I go play de Fiddle to de white petticoat."
Mary Anne retired to France and lived to the ripe old age of 76. Her story was fictionalised by her great-great-granddaughter, Daphne du Maurier in the book Mary Anne.