[2] The Fitzwilliams acquired extensive holdings in the south of the West Riding of Yorkshire, largely through strategic marital alliances.

His grandson Sir William Fitzwilliam served as Lord Deputy of Ireland from 1571 to 1575 and from 1588 to 1594; he supervised the execution of the death sentence on Mary, Queen of Scots.

In April 1742 he was created Lord Fitzwilliam, Baron of Milton in the County of Northampton, in the Peerage of Great Britain,[7] and in 1746 he was further honoured when he was made Earl Fitzwilliam, of Norborough with the subsidiary title Viscount Milton, both in the County of Northampton, also in the Peerage of Great Britain.

The fourth Earl, William Fitzwilliam, was a prominent Whig politician and served as Lord President of the Council and as Lord-Lieutenant of Ireland.

In 1782 he inherited the Watson-Wentworth estates (including Wentworth Woodhouse) on the death of his uncle Lord Rockingham, which made him one of the greatest landowners in the country.

He sat as member of parliament for Malton and County Wicklow and served as Lord Lieutenant of the West Riding of Yorkshire.

Also, Lady Mabel Fitzwilliam, a socialist politician and "an ardent pioneer in education and social welfare",[10] was a granddaughter of the 6th Earl.

The family seat of Wentworth Woodhouse was sold while the more than 80,000-acre (320 km2) estate including much of the town of Malton, North Yorkshire, was retained.

Bourne Park House and Estate, near Canterbury, Kent, England, remains in the ownership of Lady Juliet Tadgell, née Wentworth-Fitzwilliam, the only child of the 8th Earl by his wife the former Olive Dorothea Plunket.