I was interested for a long time in using a cowboy & indian metaphor (when I was a child we played 'cowboys and indians' & 'provies and brits' interchangeably).

I read eventually that a lot of American Cowboys were Irish (and, since, perhaps that a lot were black too), and that they went off and gave the 'natives' there a hard time...

My guess about the K.O.B. on the wall is that it's a 'tag' by someone in the King's Own Borderers, I have the impression that soldiers in the past were given spray cans to overwrite republican graffiti etc..