The GBP/USD was building a bull flag pattern, but the chart pattern failed to break north. The lower low is now confirming a bearish ABC (orange) zigzag pattern instead. The bears are aiming for the 61.8% Fibonacci level of wave 4 vs 3. The 61.8% Fib is the last defense of the bulls for this wave 4 (blue).
The GBP/USD is showing strong bearish momentum. This is typical for a wave 3 (gold). The breakout below 1.29 should send price towards the Fibonacci targets. Multiple wave 3-4-5 patterns can form them, which could send price all the way to 1.2750. A break above 1.2950 is not expected (red x).