Certainly looks like a Spit tail wheel, just going off the presumed dimensions, compared to the newspaper beneath it. Great find if it is from Bob Stanford Tuck's kite!
Rocketeer is probably the guy to confirm or otherwise, as he's got more Spit bits than the BBMF I reckon!
Just thinking back over forty years, when I last read Tuck's story - I seem to recall a crash landing in a Spit where he had to go under some power or telephone cables, and I think 'bounced' off a hillock or some such rising ground, before continuing to the belly landing. That could possibly account for the different locations, but of course, the wheel, if it is from a Spit, could have ended up where you found it after, for example, a mid-air collision, explosion or whatever, certainly if you're in Kent!
Try sending a PM to Tony (Rocketeer), just in case he doesn't see this thread. BTW, welcom to the forum!