FH1100
Sorry, but what you write here is also completely incorrect:
Thus, YouTube has various crash videos including one in which - I believe - Ken Wallis's brother crashes "Little Nell" when the engine quits and he doesn't get the nose down far enough.
First of all, if you mean the deadly accident in England, it was not "Little Nellie", but another test gyro designed for Royal Air Force tests.
Secondly, the reason for the accident was not an engine out, but too hight speed
and PIO in an unstable machine without horizontal stabilizer.
And, of course, it was not his brother, it was a very experienced Royal Air Force
test pilot, friend of Cmndr. Wallis.
After this accident RAF pulled back supporting the autogyro development,
or actually, Cmndr. Wallis, deeply moved, decided not to let anybody, except him, fly the thing.
But if you mean this accident:
you are again wrong, because it was Wallis himself,
just too high speed on landing (not too low) and no proper flare.
As you can see, he walked away from it.