Grabbing Gadget's ball from MaxD he was in the Royal Scots Fusiliers which is a different Regiment from the Royal Scots (Lothian).
The 2nd. Batt. were in Gib & returned home on the dates given.
LLT says this:
August 1914 : in Gibraltar. Returned to England, landing September 1914, and came under orders of 21st Brigade, 7th Division.
Landed at Zeebrugge on 6 October 1914.
19 December 1915 : transferred with Brigade to 30th Division.
19 December 1915 : transferred to 90th Brigade in same Division.
7 April 1918 : transferred to 120th Brigade, 40th Division.
26 April 1918 : transferred to South African Brigade, 9th (Scottish) Division.
13 September 1918 : transferred to 28th Brigade in same Division.