There is a fair amount of lateral movement of the rotor between the pads in the rear wheel break calipers. I have played about trying to centre the rotor as best as I can to stop the ching noise caused by the rotor touching the pads. It seems to have stopped the noise when turning the rear wheel.
However, I've noticed that when the bike is tilted (as if you were corning the bike whilst cycling) to one specific side the rotor rub returns. There is also a slight rhythmic clicking sound coming from somewhere around the rear hub when spinning the rear wheel. I'm guessing that it may have something to do with a loose or unserviced freehub?
I'm also considering buying a new disc rotor, I am not sure how straight my current one is and couldn't think of a way of testing it without having a wheel truing stand.