Not knowing the area,and mis-reading my OSmap,I found that I could not access the fort,from the embankment, I was on.It required a large detour and then within yards of starting the footpath is a sign declaring that it is considered perilous due to coastal erosion.A great start.In shot,Cliffe Fort(disused) is just to the rhs of the bush; the beige building with lots of windows.A sand and gravel works is now resident adjacent to the fort.
see http://en.wikipedia.org/wiki/Cliffe_Fort