Here are a couple of picture from Tony Condon of the 1966  Nationals GP winning Auto Union driven by Gerry Ball.
The car was built by Chris Rigby, when he read Tony Condon's book, Chris remembered the car was in his parent's loft - so here it is niecely restored. It was also driven to 3rd place in the famous  Longlife sponsored meeting in November 1966 driven by Chris himself.

To modern eyes it probably doesn't look anything special, inline motor MRRC steering, VIP guide, Airfix C type Auto Union body and powered by a Pitmann, but this was not an unusual spec for highly competitive cars at the time.    This one must surely have been well set up and well driven. 

This is probably the oldest known nationals winning car!    (A  Ken Stokes car very similar to his 64 Nats winning car still exists, but as far as we know the actual winning car hasn't survived.   The 1965 GP winner no longer exists, apparently some of teh parts were reused in later cars )

 

Nats history