In the war of course it was different. I seem to remember tht the RAF were happy to offer the priveleges of command to a late relative of mine who completed 32 missions over enemy territory as a Whitley commander (a tour) - before his 19th. birthday. Although I admit there were a few irregularities which enbled him to genuinely be in this position, he did earn a mention in dispatches and the DFC for his efforts!
P.P.