CCCC MS 123 is the unique collection of the Epistolae of Herbert of Bosham (d. c. 1194), Thomas Becket's secretary and author of a version of the Vita Sancti Thomae Cantuariensis. The Epistolae gathered here do not represent the complete version of the letters as originally conceived, since both the early and later quires have suffered losses. The manuscript was copied in second half of the fourteenth century, though its long-presumed provenance from the cathedral priory of Christ Church, Canterbury, has been disputed by Neil Ker.