There are 2 titles associated with this person.

@book{ wphp_388
  author={Maxwell,Winifred},
  year={1816},
  title={Genuine Account of the Escape of Lord Nithsdale: printed from the original letter, written by the countess of Nithsdale. to her Sister, Lady Lucy Herbert, Abbess of the Augustine Nuns, at Bruges, and which is now in the possession of CONSTABLE MAXWELL, esq. a Descendant of the Family.},
  publisher={Francis Humble & Co.},
  address={Durham},    }
@book{ wphp_448
  author={Maxwell,Winifred},
  year={1827},
  title={A Letter from the Countess of Nithsdale . . . Containing a Circumstantial Account of the Escape of her Husband, William Maxwell, Fifth Earl of Nithsdale, from the Tower of London, the 23 of Feb., 1716},
  publisher={John Rider II [36 Little Britain]},
  address={London},    }