Policeman or Train Conductor?

(From an email with minor alterations.)

So I was catching the train back from Tonbridge and as I got onto the platform, I overheard a member of the station staff talking to a random guy about how there was a problem and the train currently at the platform couldn't leave until it was resolved. Random guy said "I'm a policeman, can I help?" and the station guy was obviously relieved. They went to the other end of the platform and within a couple of minutes, the train left. I don't know what was going on as I stayed up the safe end of the platform. Two uniformed policemen (is there a new word for policemen that covers both genders?) turned up but my train came before any more of the story. Anyway, my point is that this random guy, obviously just catching a train himself, said "I'm a policeman, never fear, I can save the day." Now, it is nigh unto impossible that I will ever have cause to cry "I'm a physicist, stand aside!".

Trains always get me thinking anyway. I am in awe of train conductors. They are usually men with tatoos and piercings and pony tails (or at least on the South Eastern service they are, I notice elsewhere they are not...) and I see them and I think... they are not train conductors. That just happens to be something they do. And then the policeman... he was a policeman. It wasn't something he did- it was what he was whether in uniform or out.

These are just things that came together for me over Monday and Tuesday with no coherence at all. I want to be the metaphorical policeman but perhaps I should just be the train conductor.