[ajgriff]

I'm guessing that this is an early 1A Lyons Variac ™ (licensed by the US company General Radio for production in Australia) with a cylindrical brush so it probably wouldn't have had flattened windings or plating. Later models like my 3A version had the Duratrak contact surface coating and rectangular brushes although I believe that some of the smaller Duratrak models also had cylindrical brushes.

Alan