Rylands Latin MS 164 is one of over forty manuscript books of hours in the John Rylands Library. It was made in France in the middle of the fifteenth century and its extensive, high quality illumination associates its production with the worshop of the so-called Bedford Master. However, it has not been the subject of any sustained published research and consequently the significance of variations in the mise-en-page of the books pages has not been scrutinised. This article focuses on the variations in two replacement pages, one within the calendar and one beginning the Penitential Psalms, and in the case of the page beginning the Penitential Psalms considers whether the replacement could have been made by Sir Gregory Osborne Page-Turner, the owner of Rylands Latin MS 164 in the early nineteenth century.