Sir Thomas, a famous judge, born about the beginning of the fifteenth century, was the eldest son of Thomas Westcote, Esq., of Devonshire, and the grandson, by his mother's side, of Thomas Littleton, Esq., of Frankley, in Worcestershire, whose name and arms he assumed. He was educated at one of the universities (probably Cambridge), and removing to the Inner Temple, London, became one of the readers to that society. Henry VI. appointed him steward or judge of the court of the palace, or marshalsea of the king's household; and on the 13th May 1455, king's serjeant. In this latter capacity being also a judge of assize, he travelled the northern circuit. His prudent conduct, and his high fame as a lawyer, secured the patronage alike of the Lancastrians and the Yorkists during their protracted struggle; and Edward IV., in 1462, the second year of his reign, tendered him a general pardon, and confirmed to him his offices of king's serjeant and judge of assize. In 1466, he was appointed one of the judges of the Common Pleas, and obtained a writ directed to the Commissioners of Customs for the ports of London, Bristol, and Kingston-upon-Hull, for the annual payment of 110 marks, to support his position, and of other small contributions to supply him with robes. In 1475 he was created, along with many of the first nobility, a Knight of the Order of the Bath. He died at Frankley on the 23rd of August 1481, at an advanced age, and was buried in Worcester Cathedral, where a tomb, surmounted by a statue, was erected to his memory.

His famous work on Tenures, written in Norman French, is supposed to have been composed while he was judge of the Common Pleas, and to have been printed after the author's death, but at what date is uncertain. After passing through several French editions, it was published in English in 1539. Sir Edward Coke wrote a comment upon it, now well known by the title "Coke upon Littleton."