In 1932 Pullin joined G & J Weir Ltd's aircraft department, in Glasgow, Scotland, as chief designer to develop single-place autogyros. Pullin and his team designed a series of Autogiros before moving on to a small helicopter using two rotors mounted atop outriggers each side of the fuselage. The Weir W.5 was a single-seat helicopter powered by an air-cooled engine, and established a maximum airspeed of 70 mph. Its two two-blade, fixed-pitch rotors had swashplate-actuated cyclic control. The W.5 made its first flight at Dalrymple, Ayrshire, on 7 June 1938, when it was piloted by Raymond Pullin and it became the first British helicopter to fly successfully. By World War II the W.5 had logged eighty hours' flying time and was followed by a scaled-up version, the W.6, which was the first two-seater helicopter in the world, powered by a much more powerful DH Gipsy aero engine. Further progress on this model was prevented by World War II.