Nice CS, I like that a lot actually. Accepted. 

I should mention, that in this period of time, there is such a thing called National Service. 

http://en.wikipedia.org/wiki/National_Service_Act_1948

Effectively, a conscription for any men between 17-21, for two years. This is something I should have elaborated on- but basically, could allow for very young characters to join up into the Royal Marines, being relatively fresh blood- while other Marines may be far more experienced in things such as the Cyprus Emergency, Korean War, or the Malay Emergency.