The posts regarding co-pilot solos on the OCU reminded me that on Beverleys we flew co-pilot mutual ie 2 co-pilots, eng, nav, siggy, and ALM (no qualified captain). On one such sortie at Abingdon we had an overspeed on No 2 (the one next to the nav's ear) as we were turning base leg onto finals. The noise of a Centaurus overspeeding was enough to put the fear of God up you, without the thought of what was about to happen if the flight deck didn't sort it out in the next few seconds. Fortunately we had a very experienced eng (probably by intent) and the engine was shut down and we landed safely. Could have been very different.