I had thoughts along those lines Doug, which led me to, ideas like filling airships or similar, made sense as we are near the old WW1 airship base at Willingdon.
http://www.eastsussexww1.org.uk/polegate-royal-naval-airship-station-at-lower-willingdon/
http://hmvf.co.uk/forumvb/showthread.php?11712-Bomb-damage-near-Eastbourne-E-Sussex
http://hmvf.co.uk/forumvb/showthread.php?31227-WW1-aircraft-wire-strainers&highlight=airship
Well that's good info ruxy, if a tad disappointing :-)
Although the top coat of paint looks very much like WW1 kharki brown, under that is what looks like cockpit green.
Maybe someone has been messing about playing 'lets pretend' with it, or maybe we'll never know.
Shame Mr Google doesn't seem know anything about it either.
Bernard