Built in 1902 at Coventry, Holden motorcycle, 1172.8cc engine [1,054cc ?] with a top speed of approximately 25 mph.
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Not surprised it is on a plinth - it fetched £41,400 !
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en.wikipedia.org/wiki/Holden_motor_bicycle

{apologies for the lighting - stupid auto-setting on my camera was confused by the light levels}