Robert Carlyle gives a sensitive performance as ex-IRA member O. He could so easily have played the part as either someone shifty and not to be trusted, or gone the other way and played the martyr, luckily, the role was written very well, with no judgement either way of the political situation in Belfast, so the audience never feels they are having a political agenda shoved down their throat, we are just witnessing a slice of life as seen from the perspective of a young boy.
Carlyle there just a ray of light. He and his tiger-sneakers.)) Without him this film would be too sad. And then, he nicely added composition of Scots which play Irish. :)