Yes, in the past the British have committed loads of attrocities, but I challenge you to find one country which hasn't done so.  They were different times, when people still thought it was OK to own slaves and crap like that.  We don't go around doing stuff like that anymore, but unfortunately many other countries in this world still do so.

Like that article says (lol The Guardian), I guess the British public largely don't know about these crimes, simply because these things have been hidden away, aren't taught in schools AFAIK, and are things that people simply don't want to talk about.