A very gash manoeuvre - it consists of flying low and fast, pulling up slightly to avoid descending when inverted, then applying full aileron until upright again.
Rather like a fast 'slow roll' but without the associated co-ordinated use of rudder and elevator controls.
Pilots were killed by trying it too low, failing to pitch up sufficiently to avoid descending, then hitting the ground at around the 90 deg to go point...... As the speed decreased during the roll, the a/c would obviously be out of trim and would need increased back pressure to maintain level flight when the roll was completed.
Except in a/c such as the Gnat, 'aileron rolls' are not a particularly impressive aerobatic manoeuvre. In fact we never even taught them in the RAF!