After the breakout below the trend channel GBP/USD continued depreciating, I think the strong support level will be around 1.3350 – 1.3330.
I expect that the pair will rebound from that level back to the trend line it broke out below (in red).
For the moment, however, the main trend remains bearish and in the medium term we could expect that after the test of the breakout the pair will renew its depreciation toward 1.3100 – 1.3050. If the support holds out we may see a renewal of the upward movement.
In the alternative scenario there will be a breakout below that support and in the long term the pair will test the lowest levels it reached in the beginning of 2017.