the 160 is not his unit but a roll number -- the 'date of entry' on the medal card is the best bet.. september 1915 saw 22nd and 26th divisions enter France.. and both later went on to fight in Salonika .
... i guess perhaps 26th division for his date of entry .. that is 114, 115-116 or 117th Brigades..if you check medal cards of someone with a search for "116th Bde artillery", or similar ,you may find some officers (or more rarely ORs) identified by Brigade.. and then see if the date of entry matches .. I checked a couple for 22nd division units and they have arrived a bit early (98th, 99th 100th 101st Brigades..). . I see for example a 2Lt maclean landed in France 20/9/1915 with D battery 117th Brigade..
david