Early in 1950 it was decided to modify experimentally the original jet–driven tunnel of the English Electric Company—Aircraft Division, from a subsonic to a transonic tunnel. This was inspired by the work of Ward and Wright at Langley Field. As little was known then of the pressure ratio to operate a transonic working section, the working section area was reduced from a 3 8 square foot subsonic section which could be choked, to one square foot. The working section and diffuser for this modification were quickly manufactured from wood. In addition to the new working section and diffuser, a steel fairing was added to reduce the cross sectional area of the mixing length and so match the smaller induced mass flow.