No matter how good the systems were there was always the chance of a failure. I have no idea what type of preventative system was fitted to the Warwick but attached are a few photos of what happens when an armourer accidently fires one round through the tail of the Warwick from the mid upper turret. Even though it was only one round, of course it had to be an incendiary. The results speak for themselves.
For the record the aircraft was Warwick BV455 of 293 Squadron and the photos were taken by my late father at RAF Pomigliano.
QP