Those wheel arrangements were instigated by the NZGR, the #17 2-8-2 was owned by the Wellington and Manawatu Railway Co, a private undertaking to build a railway North of our Capital via the West Coast of the Nth Is. The Government lines were built up the East Coast.
The #17, along with the 1904 #3 (2nd) 2-8-4T were in use as a Banker out of Wellington on the steeply graded sections of line there. There were two Summits with 13 tunnels in less than 25 miles. [
en.wikipedia.org]
NZGR Class Letters are listed last.