ALREADY well known to bibliophiles at the time of its purchase in February 1852, the Bedford Hours has ever since been justifiably regarded as one of the star attractions of the national collection. Some of its illustrations, especially the lively miniatures of Noah's Ark, have become famous through frequent reproduction in popular art and history books and on greetings cards. Individual pages are often included in more serious studies of late medieval illumination because this manuscript, together with the Duke of Bedford's Breviary in Paris, has given a name - the Bedford Master - to one of the leading book painters, otherwise anonymous, of the early fifteenth century. It therefore comes as something of a shock to find that only once, as long ago as 1794, has the Bedford Hours been the subject of a full-scale published description and that discussions devoted specifically to it are equally rare.