Since the completion of the four volumes of _Roman Mosaics of Britain_ covering all of Britain to 2010, more mosaics have been discovered and research has continued. The present volume brings the catalogue up-to-date to July 2023, while the first part is devoted to various aspects of mosaic, including subject matter, context, design and manufacture. This is a lengthy overview of mosaic research, which could only be discussed on a regional basis in the previous volumes. The principal finds are the amazing figured mosaics, from Boxford, West Berkshire and Ketton, Rutland, arguably the most important discoveries in over 60 years. However, there are also numerous mosaics from other sites, illustrated along with building plans where possible, including re-excavation of known mosaics and historic recordings that have re-emerged since 2010.