appearance bunker concrete defence defend defending emplacement gun gun-emplacement gun-platform heritage historic history military pillbox secure security solid structure weapon weaponry weapons bare barren aim aimed aiming angled angles Australian-Defense-Force barrel coast coastal-defense combat-readiness death defensive destruction destructive equipment gun-turret hilltop mounted mounted-gun placed placement protection protective shrubbery trees upward vantage-point vegetation World-War-2 wwii battle camouflage-netting conflict display fighting machine-gun open-air war 2 army defense desuetude England english field fortification Great Britain Hedera II infantry ivy overgrown rural Surrey two World