The GBP/USD could also break below the support trend line (green) of the uptrend channel. In that case a bearish reversal is taking place, which would indicate that wave A (green) has been completed at the recent high and that price is then most likely building a retracement within wave B.
The GBP/USD seems to have completed a bearish ABC (light green) zigzag correction within wave 4 (dark red). Price has also bounced at the 38.2% Fibonacci retracement level and price is now approaching the key resistance trend line (red). A bullish break could confirm the wave 5 (dark red) whereas a bearish break below the 61.8% Fib of wave 4 vs 3 would invalidate the wave 4 (dark red).