[1] The wings, which were slightly swept about the spars, had a constant-chord centre section, tapering outboard with ailerons and rounded tips.

It curved to a point at the nose, where the flying wires and tow rope were attached, and tapered gently towards the tail.

[4] A rubber-sprung ash landing skid with a steel sole ran from the nose to below the trailing edge.

[1] There were no fixed tail surfaces: separate rounded elevators were mounted on a little pedestal and a roughly D-shaped rudder moved between them.

After soaring flights over the South Downs, Manuel designed and built a developed version named the Willow Wren.

The tail surfaces were also revised, with a single-piece elevator with a straighter leading edge and a taller, deeper rudder.

[5] A final development was the Dunstable Kestrel, with the same wing as the Blue Wren, a fuselage 4 in (102 mm) shorter and 35 lb (16 kg) heavier empty.

[5] The Yellow Wren was acquired and restored by the late Mike Beach and others in the mid-1990s and was sold to Brooklands Museum in Surrey in 1998.