Aviation Traders was established by Freddie Laker at Rochford Aerodrome near Southend-on-Sea, Essex, England in 1949 and was one of many seeking to develop a successor to the Douglas DC-3 aircraft that had been so prominent during and after the Second World War. The outcome of their work was the ATL90 Accountant that first flew on 9th July 1957. This was designed for 28 passengers and, like the more successful Avro 748, Handley Page Dart Herald and Fokker Friendship, was powered by two Rolls-Royce Dart turboprop engines. Unfortunately the market was saturated and the Accountant attracted no orders.

Conversion work proved more successful. Surplus military trainer aircraft such as the Percival Prentice were converted for civilian customers. Some Avro Tudor airliners were adapted to carry freight. Twenty-one Douglas DC-4 airliners were converted to car ferries, a task that included raising their cockpits high above the original fuselage and hinging a bulbous nose built beneath through which up to six cars could be loaded by means of a ground-based ramp. Twenty-two passengers could be accommodated in the remaining rear fuselage whose cross-section remained as-built. The fin and wings were enlarged to offset the added bulk and weight. Many of these piston-engined ATL98 Carvair aircraft were operated from Southend Airport on short routes across the English Channel or North Sea. The provision of such fast ferry services by large hovercraft (the SRN-4) and subsequently by Shuttle trains using the Channel Tunnel means that the age of the car carrying airliner commenced with the Bristol Freighter and concluded with the unforgettable Carvair. Commercial considerations mean that such an era is unlikely to recur.