I registered it in the UK when I lived there in 1982. The government clerk told me an old vehicle like that needed an old registration number, and that's the one he provided. In the UK in those days it was the owner's responsibility to have the registration number either painted on the vehicle or have a plate made up by a garage. I painted it on. Proof of payment of the annual tax was placed in a dinky holder stuck to the windscreen facing outwards. Ontario provides a sticker that is affixed to the rear plate. I think the plates belong to the Ontario government even though they charge the motorist for them of course.
The company shipped my family to Ontario together with my household effects including Jeep and trailer but unfortunately not my Windsor Carrier. I lent that to the IWM for display at Duxford until it was sold. The Jeep now carries Ontario plates.
By the way in the UK trailers were not separately registered but carried the same registration as the towing vehicle. In Canada trailers are separately registered and taxed. What's the practise I wonder in New Zealand?
The Jeep and trailer are now offered on E-Bay;
Item number 4549018695.