I think this is the A K mentioned on Alyth War Memorial.
Number :- Thomson, Alexander K
Service :- Army
Regiment / ship :- Black Watch (Royal Highlanders)
Date of death :- 7th August, 1917
Cemetery / Memorial :- Drumoak New Parish Churchyard, Aberdeenshire
Area of cemetery / memorial :- 203
Family information :- Son of the late David and Agnes Thomson, Mewhall, Drumoak; husband of Christina Abercrombie Thomson of Oak Cottage, Drumoak.
Extra information :-