Ahhh... Silver City
I too remember Silver City and the Bristol 170. Drive down to Lydd, hop on the plane to Le Touquet, drive up the coast to Boulogne or Calais and hop on Motorail to either Lyon or, in later years, Avignon.
I mostly remember riding in the cockpit. You went from the passenger cabin at the back into the front section where the cars were and then climbed up a ladder into the cockpit which sat over the cars. Now, at this point my memory gets a bit hazy (I was only about 10) but I recall the aircraft were fitted with a paper moving map (Decca Navigator?) which slowly rolled its' way across the Channel. The map was fitted to rollers and a pointer. As the aircraft flew so the map rolled from one spool to the other with the pointer showing the current position.