During this period there were several domestic happenings in Lady Mary's family.
On March 5, 1726, died her father, the Duke of Kingston. After the accession of George I, the Marquess of Dorchester (as he then was) was high in favour at Court, and honours were showered upon him with a lavish hand. He was in 1714 appointed Lord Lieutenant of Wiltshire, and in the same year Chief Justice in Eyre, north of Trent, which latter dignity he held for two years. In August, 1715, he was created Duke of Kingston upon Hull, in the county of Yorkshire. He held the high office of Lord Privy Seal from 1716 to 1719 in the Administrations of Townshend and Stanhope, in the latter year becoming Lord President of the Council. When Walpole became First Lord of the Treasury, the Duke again became Lord Privy Seal, and held the post until his death. He was given the Garter in 1719, and was four times named as one of the Lord Justices of the Realm during the King's absences from England on visits to Hanover. He had married, secondly, Isabella, fifth daughter of William Bentinck, first Earl of Portland, by his first wife, Anne, daughter of Sir Edward Villiers, who survived him two years.
The Duke had never really forgiven Lady Mary for eloping. Her defiance of him hurt his pride inordinately. Everyone else to some degree at least he could control; his young daughter not at all. Only so far were they ever reconciled that he would occasionally visit the Montagus at their London house and play with the children.
In his later years the Duke's health was unsatisfactory, but it was not thought that the end was so near. "I have now to tell you of the surprising death of my father, and a great deal of surprising management of the people about him, which I leave informing you until another time, being now under some spirit of hurry myself," Lady Mary wrote to Lady Mar in March, 1726. "I am unfeignedly sorry that I cannot send you word of a considerable legacy for yourself." On April 15 she supplemented this account; but not to a degree to make it very intelligible:
"To be sure, the shock must be very great to you whenever you heard it; as indeed it was to us all here, being so sudden. It is to no purpose now to relate particulars, but only renewing our grief. I can't forbear telling you the Duchess has behaved very oddly in endeavouring to get the guardianship of the young Duke and his sister, contrary to her husband's will; but the boy, when he was fourteen, confirmed the trustees his grandfather left; so that ended all disputes; and Lady Fanny is to live with my aunt Cheyne. There is a vast number of things that have happened, and some people's behaviour so extraordinary in this melancholy business, that it would be great ease of mind if I could tell it you; but I must not venture to speak too freely in a letter."
A week or so later, some further details were forthcoming:
"I received yours, dear sister, this minute, and am very sorry both for your past illness and affliction; though au bout du compte, I don't know why filial piety should exceed fatherly fondness. So much by way of consolation. As to the management at that time—I do verily believe, if my good aunt and sister had been less fools, and my dear mother-in-law less mercenary, things might have had a turn more to your advantage and mine too; when we meet, I will tell you many circumstances which would be tedious in a letter. I could not get my sister Gower to join to act with me, and mamma and I were in an actual scold when my poor father expired; she has shewn a hardness of heart upon this occasion that would appear incredible to any body not capable of it themselves. The addition to her jointure is, one way or other, £2000 per annum; so her good Grace remains a passable rich widow, and is already presented by the town with a variety of young husbands; but I believe her constitution is not good enough to let her amorous inclinations get the better of her covetous."
Lady Mary was very angry, because she heard that at the end her father had really expressed a great deal of kindness to her, and even a desire of talking to her, which the Duchess would not permit. However, he left her in his will, she having married without a settlement, £6,000 for her separate use during her life, with reversion to her daughter.
As regards the heir, she wrote: "The Duke of Kingston has hitherto had so ill an education, 'tis hard to make any judgment of him; he has spirit, but I fear he will never have his father's good sense. As young noblemen go, 'tis possible he may make a good figure among them."
The young Duke was sent to France, and there was much discussion as to what should be done with his sister, Lady Frances Pierrepont. Her having £400 per annum for maintenance, has, Lady Mary remarked ironically, "awakened the consciences of half her relations to take care of her education, and (excepting myself) they have all been squabbling about her. My sister Gower carries her off to-morrow morning to Staffordshire. The lies, twaddles, and contrivances about this affair are innumerable. I should pity the poor girl if I saw she pitied herself."