Champion
Its an interesting one this. Firstly Radiation (using that same trade mark) was a group of British companies including Jackson (Electric cookers/ranges), Parnall (washers and dryers) and New World (Gas cookers/ranges). The model names of Topline and Trimline were used for Jackson cookers and Spinwasher was used for Parnall washers - these are all mentioned in the attachment linked in an earlier reply. Parnall was the only UK manufactured washer that had any form of suds saving. I also know that the Parnall name was used for a while on Australian cookers although they don't look much like anything we saw here.
The group was amalgamated/take over by the TI group around 1967 or so and the Parnall name was swiftly dropped along with its washer lines (top loading automatic and semi automatic washers), their all new tumble dryer range was rebranded and developed under TI's Creda brand. The cookers ran alongside Creda's extensive line of cookers for a while (Jackson had a strong brand presence) although Jackson models were gradually dropped where there was duplication with Creda and finally in around 1976 the last Jackson cooker, the Topline, was rebranded as Creda.
The washers started life as a locally manufactured version of US Thor model which morphed into the very different looking Parnall Spinwasher (semi automatic) around 1959 although apparently very similar mechanically. This model was further updated and an additional fully automatic washer added.
Its perfectly possible that a NZ subsidiary might not have been included in the takeover for, whilst that agitator has the look of Parnall about it, the control panel looks far more modern than that of the last UK Spinwasher. Of course it is possible they were manufacturing them locally under licence and continued to do so - I have little knowledge of Antipodean washers but the control panel has something of the look of Australian manufactured Hoover toploaders to me. As long as the price is low it could well be worth getting and, although spare parts may be scarce, ingenuity can go a long way in getting a machine up and running. Good Luck