Knut Erik Hagen took these photos in August 2003, at the Imperial War Museum.
Bruce Dyck adds:
This is a Triumph Type A, (if it lacked the pedals it would be a Type H),
and according to Triumph: at "the outbreak of the First World War
the Type A, as it was known,
had a 550cc engine slugging out 4bhp.
The British Government placed orders with Triumph
in order to equip army despatch riders at the front."