W.L.Manuel designed and built the first four types of gliders while he was serving in the RAF. He was the Channel Gliding Club instructor in 1932. In 1933 he established a small workshop at the London Gliding Club, Dunstable (which was known as the Wren Works) and built the second Willow Wren there. At that time he advertised for sale complete Wrens at £90 and Primary gliders at £45 each. In January 1935 he joined the Dunstable Sailplane Co and built a developed version of the Willow Wren which was named the Dunstable Kestrel.
In January 1968, W.L.Manuel retired from the position of Chief Planning Engineer with A.C. Cars Ltd, and, having already designed the Hawk, built this at Fairoaks aerodrome, Surrey.