High stalls rally. Low stalls fall.
The GBPUSD is sitting in a box. When that happens the buyers and sellers are battling. At some point the price will break. However, for the time being, you need to respect the support and the resistance.
Looking at the hourly chart, the price high today stalled at the high from yesterday. That level comes in at 1.39957.
At the lows today, the price stalled twice at the same level at 1.3894 area.
In between, sits a trend line (that is becoming less important as the market consolidates in the box), and the 100 hour MA.
The price today moved above that MA line (blue line in the chart above) and failed on the first attempt. The move back below sent the price tumbling lower.
As a result, keep an eye on a re- test of that MA for short term trading clues. Stay below is more bearish. Move above is more bullish (at least a little until it reaches the top of the box.