Archibald 'Arch' Cameron is 2nd from the left. Reverse of the photo gives the information as shown in the title...the troop number is faded but believed to be 4 troop. In Jimmy Dunning's book The Fighting Fourth, 4 troop in Holland was the heavy weapons troop and commanded by Capt. Knyvet-Carr.
[Photo courtesy of Elspeth Cameron, daughter of Archibald Cameron. Posted by Pete R.]