What you are talking about with your uncle is the airspeed gap (in those days) between normal unstick speed and the higher speed at which full power on one engine and nothing on the other could be controlled by full rudder and a bit of aileron (this speed was often called single engined safety speed now V min control air - Vmca - with today's certification paperwork).
Thanks John. I'm not MEP qualified but talking to some of the guys that are at the club I was surprised to find that a lot of WWII era twins (even the Mosquito) had quite a gap between unstick and Vmca. Mu uncle's crash was as you described, lost an engine at around 100' on take off and it just rolled onto it's side and went in. Probably by the time he had figured out what had happened and throttled back on the live engine it was too late.