I know where you mean. The raised embankment used to be the Creech to Chard Railway, with the other raised embankment being the old canal. Bridges would have crossed the road at this point. They seem to have landscaped a lot of this old railway and joining field, and seem to be very keen to keep people out, their property i guess so fair enough. From memory the turret wall is just an arrangement of stones on the end of the bank and what seems to be an access slope to give the appearance of some sort of castle, Im sure its just earth underneath. However if you look closer, below this and set slightly further back toward creech and under this set of stones is a WW2 structure that is fairly substantial and travels under the embankment, with access from behind, near the smaller layby/gate entrance on the creech side ( not the big lay by used by wsseex water, the other side ). It was til fairly recently possible to enter this structure, I suspect the current owners have most likley blocked this off for their own use. Again they seem to have added some stones to give it some sort of castle effect. there are other structures on this embankment including what i assume is a train stop and a pill box, most easily seen from the road from Henlade to Creech, just past the single bungalow on its own. Really not sure what its all about but im guessing they are doing more to preserve the structures than the damage used to be done to it by off roaders....unless they still use it and this is part of making it more attractive to members of an off road club? I notice the canal embankmenton the other side of the road had been very much 'tidied up' so dont know if this has the same owners.