Lady Mary Booth (1704-1772) was the only child of George Booth (1675-1758), 2nd Earl of Warrington, and his wife Mary Oldbury, the daughter of a wealthy London merchant, who brought him a fortune estimated at £40,000. The marriage was not a happy one, and it failed to produce a son to continue the Booth line at Dunham Massey. Instead the 2nd Earl of Warrington appears to have focused all his affection and concern on his only daughter, Mary (1704-1772), who was trained to assume responsibility for the management of the estates. In 1736 Mary Booth married Harry Grey, 4th Earl of Stamford, the two families already being associated by the marriage in 1644 of George Booth (1622-1684), 1st Baron Delamer, to Lady Elizabeth Grey, daughter of the 1st Earl of Stamford.
Under Lord Warrington's will Dunham Massey and the Booth estates were vested in two trustees, George and Thomas Hunt, on behalf of Mary during her lifetime (as a woman she could not own the property herself), subject to a proviso that her husband should have no power or control over them. Whatever the legal position, Mary Countess of Stamford was the de facto owner of the Booth estates and took a keen personal interest in their development. On her death in 1772 Dunham Massey passed to her son, George Harry Grey (1737-1819), 5th Earl of Stamford.