Nice

A photo of the engine would be good.
Unfortunately, I cannot have a look at my Drive as the car is in Lincolnshire.
I dont think it uses rubber couplings so yours is likely to be an early car. However, the 10" wheels dont suggest a very early car.
Denis' website has a lot of info.
http://www.microcarfan.com/index.php/marques/74-willam