In 1984-85, part of the medieval painted scheme on the crypt vaults of Rochester Cathedral underwent conservation treatment by the Perry Lithgow Partnership. As is usual with British wall paintings, excessive damp together with the past application of an organic fixative had caused the paint to separate from the ground, and severe darkening had made the subject matter on these paintings extremely difficult to read. Exceptional difficulties were encountered in the cleaning stage. After a survey of their historical background, the past treatment and condition up to 1984 are reviewed. The 1984-85 work of removing, cleaning, consolidating, and reattaching the wall paintings using an improved <i>strappo</i> method is examined in detail. It is intended that this program will continue as a new type of collaborative venture in wall-painting conservation in England between a private workshop and the corresponding training course at the Courtauld Institute. Acknowledgements and a list of materials and suppliers are appended.