The Fairthorpe Atom was an experiment in fiberglass. It was the first product of Fairthorpe Ltd., a car company founded by Air Vice Marshall D.C.T. Bennett CB, CBE, DSO (an RAF officer, airline founder, and member of Parliament).
As quoted on the Fairthorpe Sports Car Site, "In the mid fifties fibreglass was in it’s infancy and everyone was learning how to work it including Don Bennett. His first attempts at car manufacture produced what we today would call a microcar, seating just two people and using a motorcycle engine in the rear. It was called the ATOM but perhaps did not go like one. The Excelsior two stroke, BSA 250cc and Gold Flash 650 engines were options but despite a great deal of development work and export orders from America, the car was not a great commercial success."
But...the Atom was the forerunner of the Fairthorpe Electron, a more substantial sports car that enjoyed greater success.