Yep, in recent years a GP joined the RNR as a Rating as that's what they wanted to do.I liked to gently taunt a friend (he's a Royal Marine so if I overdid it he might kill me) by asking whether he was properly addressed as 'Sergeant Doctor...' or 'Doctor Sergeant...' (he's since been persuaded into a commission - needs of the service rather than his preference, he's a top bloke regardless).
Lots of very bright, well-qualified Other Ranks out there if you look..
Similarly the RMR had a bloke who was a prof at CERN (the Hadron Collider thingy) and he was a Mne1 HW.
Likewise there's an RM SF Brigadier who will tell anyone who will listen, in his broad Scouse accent, that he was told when he joined at Liverpool AFCO that he'd never make Officer as long as his Arrse pointed downwards.
To be fair, he never made it as a regular RM GD Officer, though