The 13th-century charnel house, as one of only two surviving in Britain, is a valuable osteological resource. A multidisciplinary study of the deterioration mentioned by previous workers included recording the crypt's humidity and making some histological observations; it was found that destructive processes are accelerating. The bones need to be removed, thoroughly cleaned and dried, treated with fungicide, and restored to a correctly prepared and humidified crypt for their long-term preservation.