I feel this image shows very clearly the "sit" of a tower on a motte,after re-building in stone.Very often I'll look at a small motte and think that no way could it ever have supported a meaningful tower,but this image,quite demonstrably,illustrates how such was done.
see http://www.ecastles.co.uk/hopton.html
see http://www.castlewales.com/hopton.html
see http://www.castles99.ukprint.com/Essays/hopton.html
see http://www.channel4.com/programmes/time-team/articles/hopton-castle-by-stewart-ainsworth
see http://liberalengland.blogspot.com/2010/05/time-team-at-hopton-castle.html
Since the Time Team programme was aired,many changes have been enacted at Hopton Castle.The structure has been repaired and now access to the inners of the keep, allow visitors access to a much repaired and strengthened tower.Information boards abound; even provided with a neat little car park for visitors.