Her amours in general, and her intimacy with the rope-dancer in particular, becoming common talk of the town, his majesty became incensed; and it grieved him the more that one who dwelt in his palace, and was yet under his protection, should divide her favours between a king and a mountebank. Accordingly bitter feuds arose between her and the monarch, when words of hatred, scorn, and defiance were freely exchanged. His majesty upbraiding her with a love for the rope-dancer, she replied with much spirit, "it very ill became him to throw out such reproaches against her: that he had never ceased quarrelling unjustly with her, ever since he had betrayed his own mean low inclinations:
that to gratify such a depraved taste as his, he wanted the pitiful strolling actresses whom he had lately introduced into their society." Then came fresh threats from the lips of the fury, followed by passionate storms of tears.
The king, who loved ease greatly, and valued peace exceedingly, became desirous of avoiding such harrowing scenes. Accordingly, he resolved to enter into a treaty with his late mistress, by which he would consent to grant her such concessions as she desired, providing she promised to discontinue her intrigues with objectionable persons, and leave him to pursue his ways without reproach. By mutual consent, his majesty and the countess selected the Chevalier de Grammont to conduct this delicate business; he being one in whose tact and judgment they had implicit confidence. After various consultations and due consideration, it was agreed the countess should abandon her amours with Henry Jermyn and Jacob Hall, rail no more against Moll Davis or Nell Gwynn, or any other of his majesty's favourites, in consideration for which Charles would create her a duchess, and give her an additional pension in order to support her fresh honours with becoming dignity.
And as the king found her residence in Whitehall no longer necessary to his happiness, Berkshire House was purchased for her as a suitable dwelling This great mansion, situated at the south-west corner of St. James's Street, facing St. James's Palace, was surrounded by pleasant gardens devised in the Dutch style, and was in every way a habitation suited for a prince. This handsome gift was followed by a grant of the revenues of the Post Office, amounting to four thousand seven hundred pounds a year, which was at first paid her in weekly instalments. On the 3rd of August, 1670, Barbara, Countess of Castlemaine, was created Baroness Nonsuch, of Nonsuch Park, Surrey; Countess of Southampton; and Duchess of Cleveland in the peerage of England. The reasons for crowding these honours thick upon her were, as the patent stated, "in consideration of her noble descent, her father's death in the service of the crown, and by reason of her personal virtues."Nor did his majesty's extravagant favours to her end here. She was now, as Mr. Povy told his friend Pepys, "in a higher command over the king than ever--not as a mistress, for she scorns him, but as a tyrant, to command him." In consequence of this power, she was, two months after her creation as duchess, presented by the monarch with the favourite hunting seat of Henry VIII., the magnificent palace and great park of Nonsuch, in the parishes of Cheam and Malden, in the county of Surrey. And yet a year later, she received fresh proofs of his royal munificence by the gift of "the manor, hundred, and advowson of Woking, county Surrey; the manor and advowson of Chobham, the hundred of Blackheath and Wootton, the manor of Bagshot (except the park, site of the manor and manor-house, and the Bailiwick, and the office of the Bailiwick, called Surrey Bailiwick, otherwise Bagshot Bailiwick), and the advowson of Bisley, all in the same county."Her wealth, the more notable at a time when the king was in debt, and the nation impoverished from expenditure necessary to warfare, was enormous. Andrew Marvell, writing in August, 1671, states: "Lord St. John, Sir R. Howard, Sir John Bennet, and Sir W. Bicknell, the brewer, have farmed the customs. They have signed and sealed ten thousand pounds a year more to the Duchess of Cleveland; who has likewise near ten thousand pounds a year out of the new farm of the country excise of Beer and Ale; five thousand pounds a year out of the Post Office; and they say, the reversion of all the King's Leases, the reversion of places all in the Custom House, the green wax, and indeed what not? All promotions spiritual and temporal pass under her cognizance.".