I believe that I have found what happened to Thomas Hall.
The Medal Rolls for the 1/6th Battalion Highland Light Infantry shows that he was commissioned on 21.1.1916 -- this lead me to searching for a
Lieutenant Thomas Hall.
I found an obituary in the newspaper The Scotsman published on the 31st October 1917. It reads:
Lt. and Quartermaster Thomas Hall, H.L.I., who has died in Yorkhill War Hospital, Glasgow, was a native of Perth. His military service extended over a period of twenty-three years. He had served in India, Egypt and South Africa, and held the Queen's Medal with clasps and the King's Medal with clasps for service in the Boer War. He had been Lieutenant and Quartermaster since JANUARY 1916. He was with the Mediterranean Expeditionary Force in Gallipoli from May 1915 to October 1915, when he was invalided home, and the recurrence of trouble from an accident which had befallen him at the Dardanelles was the cause of his death. His remains were interred with military honours at Kilmarnock, where his widow resides. Prior to joining the Army he was a telegraphic superintendent with the Caledonian RailwayTwo things in the above which points that this is Thomas Hall 1395, is the date he became a Lieutenant, January 1916 - ties in with his medal rolls entry. The second is that he was in Gallipoli, ties in with his medal rolls entry (theatre of war '2b') -- the obit says from May 1915 but his medal rolls entry states 2 July 1915.
The link below will take you to an obituary taken from the newspaper the Perthshire Constitutional and Journal, 7th November 1917. This will also show you his photograph.
https://eheilmann.com/2012/08/27/thomas-obituary/The next link below will take you to FindAGrave where you will see that he does have a link to New Zealand, i.e. a notation reads
Additional
Information:Son of William and Lydia Celina Hall; husband of Sarah Purdie Hall, of 22, Hauraki Rd., Takapuna, Auckland, New Zealand. Born at Perth.https://www.findagrave.com/memorial/156026295/thomas-hallHope this assists the OP
Added -- Thomas Hall married Sarah Purdie Barnes in 1916 with the marriage taken place in the Kilmarnock area of Scotland. I have tried to find when Sarah emigrated to New Zealand but haven't found anything yet.