It was almost completed by April 1945, when American troops liberated the prisoners being held in Colditz.
The idea for the glider came from Major Tony Rolt who noticed that the lower roofline of the chapel could not be seen from any of the German sentry posts. The two-man craft, designed by RAF flight lieutenants Jack Best and Bill Goldfinch, was built in the lower attic of the chapel. It was to be launched from the roof of the adjacent sick ward, which was one storey lower than the chapel.
It was intended that a runway be built across the sick ward roof out of tables held together by bed slats. The glider would accelerate to its flying speed of 30 knots by being placed on a small trolley mounted on runners that ran along the runway. The trolley was tied to a bathtub filled with concrete, which was to be thrown off the far end of the sick ward roof, so that as it fell it pulled the glider along the runway.
The only known photo of the Cock shows it standing facing a row of windows, all of which are far too small for it to exit. This is, in fact, the south side of the attic. The glider was to exit via the western end, through a larger window. Even so, with a wingspan of 32 feet and a fuselage 19 feet 9 inches long, it was too big to be got out in one piece. The wings were detachable from the fuselage so that they could be taken out separately and bolted on to the fuselage for launch.
Rupert Matthews, historian and author.