The Manuel Crested and Willow Wrens formed a series of wooden, single-seat gliders designed in the UK by W. L. Manuel in the early 1930s, intended for slope soaring. Some were built by the designer, others from plans he supplied. The Dunstable Kestrel was a further development. Design and development The Crested Wren was the first of the series, its design influenced by contemporary German practice. It was built by Manuel. Its two-piece wings had single spars which, together with plywood wing coverings forward of them, formed D-shaped box girders. The wooden ribs were produced in batches with a method devised by Manuel. Behind the spar the wings were fabric covered. The wings, which were slightly swept about the spars, had a constant-chord centre section, tapering outboard with ailerons and rounded tips. There were no flaps or airbrakes. The wings were mounted on a fuselage pylon and had lift struts from the lower fuselage. Two flying wires from the nose assisted with drag or torsional loads. The Crested Wren's fuselage was a plywood-skinned hexagonal structure, its vertical faces longer than the others. It curved to a point at the nose, where the flying wires and tow rope were attached, and tapered gently towards the tail. The open, unscreened cockpit was under the wing leading edge immediately forward of the pylon. A rubber-sprung ash landing skid with a steel sole ran from the nose to below the trailing edge. There were no fixed tail surfaces: separate rounded elevators were mounted on a little pedestal and a roughly D-shaped rudder moved between them. The elevator control wires emerged from the fuselage midway between the wing and the tail. The first flight of the Crested Wren was in July 1931. After soaring flights over the South Downs, Manuel designed and built a developed version named the Willow Wren. This was very similar to the Crested Wren but had a deeper cockpit which left the pilot less exposed. The tail surfaces were also revised, with a single-piece elevator with a straighter leading edge and a taller, deeper rudder. The elevator modification allowed the control wires to run within the fuselage. The deeper rudder added 35 mm (1.4 in) to the glider's length but all other dimensions were the same. The redesign increased the empty weight by about 20 lb (9 kg). The Willow Wren prototype first flew in December 1932. The Willow Wrens built