Intreguing mentioning he was a despatch rider.
IMI perhaps Julian, though no trace in Robert Hope's lists of IMI.
One for you and Bill to investigate perhaps[You must be registered and logged in to see this image.]
Portsmouth Evening News - Wednesday 05 January 1927
A cursory look through Duttons in the Imperial regiments shows two A Barkers.
45/352 A Barker 2/3rd Regiment 1879 clasp
2202 A Barker 2/21st Regiment 1879 Clasp