From The Bowies and Their Kindred, p 394-5.
Capt. Thomas Clagett, son of Col. Edward Clagett (1613-1670) of London, England, and his wife, Margaret Adams, was born about 1635—40, in England, and for a time was an officer in the British Navy. He inherited landed estates in England, but about 1670 emigrated to Maryland, and settled in St. Leonard's town, on St. Leonard's Creek, Calvert County. He was apparently .possessed of considerable means when he arrived in America, as he at once purchased, and received by royal grant, a number of large tracts of land in various parts of the Province, such as Goodlington Manor," one thousand acres on the Eastern shore; “Weston," eight hundred acres, on the Western branch, near Upper Marlborough; " Greenland," near the " Wood Yard," and Croome," in what is now Prince George's County, as well as a large tract near St. Leonard's town.
His name frequently appears on the early archives of the Colony, and he is always spoken of as " Captain Thomas Clagett, Gentleman." In 1683 he was appointed Coroner of Calvert County. In 1689 he is mentioned as one of the prominent Protestants who refused to participate in the revolt against the Roman Catholics. His wife was Sarah Patterson, of London, England. She joined him in a deed of entail to their son Thomas Clagett, Jr., of the estate known as " Weston," which had been first surveyed in 1671 for Charles Boteler, and sold by him to Captain Clagett. The deed was signed by John Smith, justice of the peace for Calvert, the maternal uncle of John Bowie, Sr.
Captain Clagett executed a will in 1703, which was probated in 1706. He devised to his son, Edward Clagett, the " land I inherited in England from my father, Col. Edward Clagett." His son, Thomas, having received "Weston," was not mentioned; but Croome was given to his son Richard; "Greenland" to his son John; land in Calvert County to Charles (who was later a magistrate), and another tract to the youngest son, George. He left money to his daughters, Martha Clagett and Elizabeth Wardsworth, and the widow received the property in St. Leonard's Town [Maryland].
The appraisements of his household effects was enumerated according to the rooms in which the furniture was located, and mention is made of a large hall in which hung a map of Maryland and family portraits. It is worthy of note that this first representative of the family in America invariably spelled his name with but one g, and the first of his descendants who altered the spelling was his great-grandson, Bishop Thomas J. Claggett.
Captain Thomas Clagett's autograph, as well as that of his wife, is found on the parchment deed of entail for "Weston," the original document being now in the possession of Mr. W. B. Clagett, his great, great, great, great, great-grandson. Captain Thomas Clagett and wife are supposed to have been buried at St. Leonard's town, where he lived and died. Their descendants are very numerous, and we have only a partial list of those sprung from two of the sons. Edward is supposed to have returned to England, as his inheritance was there located.
From Bowie, Walter Worthington. The Bowies and Their Kindred. A Genealogical and Biographical History 1858-1938.