Caledon was moved to the Central Region because the GTR was re-assigned to Highway Safety Division.
The other detachments in the HSD are Whitby, Aurora, Toronto, Port Credit, Burlington, Niagara, Cambridge and Barrie.
Their primary role in policing is highways, as all those areas have their own Municipal/Regional Police.
Caledon's mandate is to provide community Policing.
It doesn't make much sense to have a community police service lumped in with Highway Janitors.