According to a pedigree, duly certified by the French heraldic authorities in the year 1652, Lord Northwick's ancestor was Thibaut Rushaut, a noble English knight (nolle chevalier Anglois), who settled in France at the commencement of the fourteenth century. His posterity were Lords and Marquises of Gamaches, one of whom was of the number of the five Protestant nobles who escaped the massacre of St. Bartholomew, in consideration of being related to Catherine de Medicis. His son settled in Flanders, and his descendant, John Rushout, a native of Rousselaer in that country, settled in England, and died in 1653. His son, James Rushout, was created a baronet at the Restoration of Charles II.

The name of a British M. P. (1857). James Rushout was created a baronet at the Restoration of Charles II. An ancestor of the Rushouts was Thibaut Rashaut, a noble English knight. The name may be derived from some Dutch or Flemish local name ending in hout, signifying wood, timber. compare the Flemish Turnhout and the English local names Bagshot, Oakshot, compounded of holt, a wood or grove. Rushout or Rushaut may also be a corruption of the French name Rousset, Roussell, Russell, diminutives of Roux.

Or Rouault, a baronial family. This family is Breton, deriving from Roald or Rouault, a Breton noble living c. 1000, whose son Hasculph, Viscount of Nantes, c. 1050, had four sons, who accompanied the Conqueror, viz. 1. Ruald;2. Hasculph; 3. Hugh; 4. Enisand. See Conyngham. Ruald, surnamed Adobé (i.e. dubbed knight), held three lordships in capite 1086 in Devon (Domesday, 114 b). His son Ruald was father of Alan Fitz-Ruald, who m. Lady Alis de Dodbroke, and acquired estates by her (Pole, Devon). Roald Fitz-Alan, his son, had John Fitz-Rohaut, father of Alan, whose grandson Sir Roger Fitz-Rohault had a dau. and heir (Pole). Theobald Rouault, a younger son, became seated in France temp. Edward II., as Sire de Boismenard. From him descended Joachim Rouhault, Marshal of France, who d. 1478, and whose posterity settled in England t. Charles I., from whom descend the Barons Northwick.