Thoughts on the cause - I thought BAC 1-11's if they lost power went into super stall, where they are very difficult to get the nose down due to aft C of G at the point of stall; as the nose comes up, it is even harder to get back down till descending backwards (Hence why stick shakers were invented).
Presumably it should have been able to climb out (or fly at a level) on a single donk, so is it an unfortunate dual system failure?