GBPUSD broke above the downward price channel on 4-hour chart, suggesting that the fall from 1.6164 had completed at 1.5423 already. Further rally to test 1.5779 key resistance would likely be seen, a break above this level could trigger another rise towards 1.6500. Support is now at 1.5561, only break below this level could indicate that lengthier sideways movement in a range between 1.5423 and 1.5779 is underway.