As an impressionable youngster in my early teens I was lucky enough being able to get an ride in a diesel shunter, the second driver? Was a big guy who was strong enough to turn the starter by hand without the big brass key, it had a square hole in it and if my memory is correct (this happened over fifty years ago) this guy could turn the handle without the key. Question is was he winding me up or was it possible to turn the key with your bare hands? This guy was immensely strong to me anyway at that time.