Since as the scale appears to be in inches, and there is more info maybe required,..
Does it seem to have an 'axle' area for a wheel to mount to (bent, broken or unknown connection/mount), any greasing nipples or hydraulic pipe connections and similar possible interesting engineering points?; like the possible uptravel or locking down stops on the 'shoulder' near the spar/structural rotational mounts, and the small lightweight U/C door/cover link if its not a 'swing (anti-twisting) link'.
By its size - or lack of it, I'd say its certainly for a fighter-ish A/C; most likely single engined, unless its a hydraulic actuator, since it was found in what sounds like the Thames Estuary, then initially BoB related comes to mind.
Possibles to check pics against for U/C design/componants.. Hurricane, Spitfire, Defiant, Oxford, Hudson, Hampden, Skua, Typhoon/Tempest; as a part of the U/C assembly, hence lack of long axle looking thing at its other end.