Elswhere on MLU there has been mention of
this site which has some film clips from Combined Ops Trials in Woolacombe (Devon or Dorset). Though not a tread-head myself, I thought I would post these screengrabs.
1 is described as a Backburn Carrier, 2 a Straussler Carrier and 3 a Kapok Carrier (modified) - sorry I couldn't get better shots
Noel