Thanks for the advice and offers everyone. Really helpful and, against all my preconceptions, I was steered towards buying a new watch which I really wasn't expecting. He's 18 and will hopefully have enough years with this for it to tell his story... and being on a NATO strap he can chose a nice perforated leather / mesh / oyster type bracelet if he wants without feeling like we've wasted money on it..
It really resonates with me too as it kind of blends the 50's / 60's vibe I inevitably seem to get drawn towards...
..not to mention the fact that, if he doesn't like it...
Thanks for all the help and guidance..