There is a likely looking pension record on Ancestry!
319437 Gunner John Allen Hutton, Royal Garrison Artillery. (Cap badge is consistent with this, I think. Can you read his shoulder titles?)
Address: 21 Linton St, New North Rd, London. Enlisted 29/4/15, aged 24 years 334 days.
Discharged 12/3/19 from 37th Anti-Aircraft Company RGA. Profession Carpenter's Labourer. Wife Louisa, address as above.
He served in various home defence units of the RGA and Royal Field Artillery in the UK. He did not serve overseas at all (possibly due to a hernia he suffered in Oct 1915, for which he claimed a pension), hence there is no Medal Index card for him.
Hope this helps,
Adrian