The towing capacity in those days was the
unladen weight of the towing vehicle (at least in NSW):
Under Section 115(1) of the Motor Traffic Regulations (1935), it was an offence to:
(stand/drive) a (motor car/station waggon), to wit, (registration), upon a public street, to wit, (street), having attached to the rear thereof for the purpose of being towed a (vehicle/trailer) whose laden weight exceeded the unladen weight of the said (motor car/station waggon).That law was repealed with the introduction of the Motor Traffic Amendment (Towing and Mass Limits) Regulation 1998.
The law now says you must not exceed the capacity of the towing attachment or the
laden weight of the towing vehicle.
FWIW the unladen weight of a FC wagon is 2533lbs, close enough to 1.15 tonnes. I've never seen a load capacity (laden weight) published for sedans/wagons, but the utes/vans are rated at 29cwt, which equates to 1.48 tonnes.
There you go, you've learnt something today
cheers
RET