The site below gives a bit clearer understanding of Military Districts.
http://www.canadiansoldiers.com/orga.../districts.htm
Scroll down to reach the WW2 listings, it also gives a brakdown of the Brigades in each area. This leads me to a change of mind regarding Thomas due to the listing in MD3.
Could he possibly have been a Gunner - there are 3 Artillery Brigades listed in the District for that period. Add to that, Stockton was not that far from the Ranges at Warcop, about 50 miles/80km. It was also relatively close to a number of railheads and the docks on the Tees and Tyne.
Paul.