It acquired the WJ classification when the publicly owned New Zealand Railways Department (NZR) purchased the WMR and its locomotive fleet in 1908.

[3] A large 2-8-4T tank engine nicknamed Jumbo, it was based at Wellington for all its life.

[5] Jumbo was allegedly hated by both drivers and firemen, but all agreed that it was extremely strong and durable.

Like all Baldwin locomotives, it had cast bar frames; in this case, they gave considerable trouble, for they persistently broke immediately behind the smokebox saddle.

With a tendency for breaking its frames on the heavy banking duty, Jumbo saw little service after 1920.