I read a book “The Thousand Plane Raid”, and in it I recall there were men bailing out of the plane, one had to sit on the floor, and the next person had to nearly sit on his shoulders to get out. It was apparently a very small, awkwardly placed hatch. I have heard there were four escape hatches, but they must have been difficult to get out of.
As I recall from reading one of his books a long time ago, Dyson worked in “operations research” for Bomber Command, dealing with things like the percentage of crews who survived bombing missions. It was discovered that if the escape hatch was enlarged by only 2 inches, many lives could be saved. This change was recommended to higher-ups, but it was never implemented. Dyson seemed bitter that, despite this failure, the head of Bomber Command was later knighted. Dyson later became famous for work in mathematical physics and is a well-known “climate skeptic”.