There was no American connection regarding the drops on this bike.
I must admit, I assumed as much would be obvious to the casual observer...
In 1984 Britain, Mountain Bikes were very rare and even pictures of them were difficult to find as there was little MTB coverage in the cycling press. The main source of images were in handouts and brochures from bikeshops who were awaiting the first examples to roll off the production lines.
However, around the time I bought the F.W Evans there was one book by Rob Van der Plas called the Mountain Bike Book. On pages 58 & 66 there are photos of Jacquie Phelan with a dropped barred Cunningham. So in theory I could have been influenced.
In reality, the bars on the early mountain bikes were very wide, which was both wonderfully different but not very practical for the London traffic or the narrow gaps between the trees in your average English forest. So drops seemed the best solution for my new, multi-functional bike.