Early article by Derek Renn which produced a classification scheme for mottes (and ringworks) which had some following although not now much used. The limitation of the scheme was made clear by Renn's own choice to use Kilpeck and South Mymms as examples of mottes of the same type (Be2), later excavation showed the very different forms of these castles. Also has an inventory of 'temporary' castles (Siegeworks and precursor sites) which is also not very successful. This list seems to be based on 'castles' that are close together, it has a number of sites not consider castles by other authors and the attribution of sites as siegeworks or precursor is somewhat arbitrary.