Thanks bookworm. You're absolutely right about the operation of the propeller control unit (CSU)The significance of the supercharger is that if the engine rpm is maintained and the supercharger is engine driven (as compared to a being turbo-charged), the boost (manifold pressure) and charge temperature will be maintained.
So you've got a dead engine - causing drag - that maintains the same RPM, Boost, Charge temperature and oil pressure as the functioning engines.
If you were totally distracted at the time of the failure - setting up an attack on a submarine or dealing with another emergency (an electrical fire in the fuselage), the failure could be missed until the aircraft has slowed down.......which I agree on a twin would be pretty quickly but with another three engines it takes a bit longer.
411A..............my information is NOT incorrect, I've had it demonstrated to me, seen it and done it. Have you any experience of multi-engined British piston engined aircraft ?