One of the 1940 'Defiant' series of radios - the name being part of the marketing machine / war effort.
Valves (6 + eye):
Chassis Notes (most schematics can be clicked to download a full size version): 5 + eye or 6 + eye - not sure. No circuit held, more information would be appreciated.
General Construction Notes for Radio Corporation of New Zealand Ltd: The first digit of the serial number typically indicates the year of manufacture of RCNZ chassis' (although not the decade - that requires a little knowledge of the valves, construction, etc). Sets from around 1934 onwards were often (but not always) constructed in a distinctive pressed 'baking pan' style chassis, seemingly unique to RCNZ.