One source has Richard as the father of Thurstan -
http://www.afn.org/~lawson/d0003/g0000039.html#I6441
He served in the military in 1066 in Hastings, Sussex, England. FALAISE ROLL of Companions of William the Conqueror.
The name Banastre was derived from Banastre, now Beneter, near Etampes, and Camden says it is the title of office latinized into Balneator, master of the bath. Robert Banastre came to England at the conquest and an ancient pedigree of this family, beginning with Robert down to the time of Edward I, is preserved on the rolls of parliament. He held Prestatyn, one of the hundreds of Flintshire, under Robert of Rhudlaw (De Rodelent), a kinsman of the Conqueror, where a castle was built which was destroyed by
the Welsh during the reign of Henry II. The family then withdrew to Lancashire, where they held possessions under the earl of Chester. In a deed of 1106, Richard Banastre, a baron of Cheshire, appears, and in 1128 is a witness to a charter of Robert De Meschines. He also held in capite
in Shropshire, under Henry I, as lord of Munslow and Aston-Munslow in 1115. Later on the barony of Newton and the lordship of Walton-in-the-Dale passed through the female line to the Langtons, where they remained for about 300 years. The family spread to many parts of England. A member of the Lancashire Bannisters was a knight of the order of the Garter. The name appears on the rolls of Holinshed, Duchesne and Leland.