Sir Thomas Grosvenor, 3rd Baronet

Sir Thomas Grosvenor, 3rd Baronet (20 November 1656 – 2 July 1700) was an English Member of Parliament, and an ancestor of the modern day Dukes of Westminster. He was the first member of the family to build a substantial house on the present site of Eaton Hall in Cheshire.

Early life and education Grosvenor was born at Eaton Hall, Cheshire, the son of Roger Grosvenor by his wife, Christian (or Christine), daughter of Thomas Myddleton of Chirk Castle, Denbighshire. He was less than five years old when his father, Roger, was killed in a duel with his cousin, Hugh Roberts, on 22 August 1661. Roger had been the son and heir of Sir Richard Grosvenor, 2nd Baronet, and therefore, Thomas succeeded to the baronetcy upon the death of his grandfather on 31 January 1665. He was eight years old at that time. On his return, he set about building a new house at Eaton. At that time, the family house was a medieval moated house. The new house was the first substantial one to be built, and it was constructed to the north of the older house. Grosvenor appointed the architect William Samwell to design it, and building started in 1675. By 1683, over £1,000 (£ ) had been spent on the hall. The money for this venture came partly from the estates, and also from coal and lead mines, and from stone quarries in north Wales, that were owned by the family. The marriage proved to be harmonious and conventional. The land Mary brought to the marriage was later to become the Mayfair, Park Lane, and Belgravia areas of London; the most valuable parts of the Grosvenor Estate.

The couple had three daughters and five sons. Two of the sons, Thomas and Roger, died young; the other three sons all succeeded in turn to the baronetcy, Richard became the 4th Baronet, Thomas the 5th, and Robert the 6th.

Mary, Lady Grosvenor, had converted to Roman Catholicism shortly after coming of age.