Thomas Chestre was the author of a 14th-century Middle English romance Sir Launfal, a verse romance of 1045 lines based ultimately on Marie de France's Breton lay Lanval. He was possibly also the author of the 2200-line Libeaus Desconus, a story of Sir Gawain's son Gingalain based upon similar traditions to those that inspired Renaut de Beaujeu's late-12th-century or early-13th-century Old French romance Le Bel Inconnu, and also possibly of a Middle English retelling of the mid-13th-century Old French romance Octavian.Geoffrey Chaucer parodied Libeaus Desconus, among other Middle English romances, in his Canterbury Tale of Sir Thopas.
The name Thomas Chestre occurs only once in medieval writings, in the single manuscript copy that remains of the late-14th-century Middle English verse romance Sir Launfal. It is found in British Library MS Cotton Caligula A.ii, fols 35v-42v, dating from the first half of the 15th century
Lying to either side of this tale of Sir Launfal in British Museum MS Cotton Caligula A.ii, are an Arthurian tale of the Fair Unknown, Libeaus Desconus, fols 42va-57rb, and an 1800-line verse romance known as the Southern Octavian, fols 22va-35rb. On stylistic evidence, there has always been some question whether these two flanking poems in Cotton Caligula A.ii might be attributed to Thomas Chester as well, with arguments on both sides.Libeaus Desconus is found in five other medieval manuscripts. A 14th-century Middle English Octavian occurs in two other manuscripts in a version that is definitely not by Thomas Chestre, the story is arranged in a different way and it is known as the Northern Octavian.