Dr.Mopp Car 
A friction drive car by Louis Marx in Swansea,and carrying a 1967 copyright.

Made of plastic with metal components,and no more than 4" tall.
Its' only selling point was a 'push and go' friction drive mechanism.

And,all-in-all,a rather curious one really. And "curious" for 2 reasons :-

1} Because it was a one-off,even though there were plenty of other Camberwick vehicles they could have done as well.


2} Because,with the best will in the world,I can't imagine any kid pestering their parents to buy a one-off Dr.Mopp product.

All of which may go some way to explaining why it's not that difficult to pick up a nice boxed example -many of which are so good that you have to presume they were unsold stock.
​And,maybe,one of those items that's found a more receptive market among today's collector's,than it did with its target audience when first sold.