WESTMINSTER, MARQUESSES AND DUKES OF. The title of marquess of Westminster was bestowed in 1831 upon Robert Grosvenor, 2nd Earl Grosvenor (1767-1845), whose grandson, Hugh Lupus Grosvenor (1825-1899), was created duke of Westminster in 1874. The family of Grosvenor is of great antiquity in Cheshire. The ancestors of the dukes of Westminster, the Grosvenors of Eaton, near Chester, were cadets of the knightly house of Le Grosvenur. Their baronetcy dates from 1622.