CCCC MS 258 is one of two manuscripts in the Parker Collection that was once bound in a single volume, the other being the material now contained in CCCC MS 70. Both manuscripts were the property of Andrew Horn (d. 1328), fishmonger and Chamberlain of London and were bequeathed by him to the Guild Hall in London, from where Parker acquired them. CCCC MS 258 now contains fourteenth-century copies of the anonymous law tracts Speculum justiciarorum and Breton. The Speculum is a unique survival in this manuscript and was much criticised by F. W. Maitland as, at best, a joke in poor taste, though recent attempts have been made to rehabilitate the text as an expression of late thirteenth-century anxiety about the direction of legal reform under Edward I, or possibly as a didactic text.