The GBP/USD pair is trading at 1.2740 at the time of writing. As you can see on the H1 chart, the rate dropped below the uptrend line which represented a downside obstacle. Dropping below this line signaled that the uptrend ended and that the rate could develop a new downtrend.
It has dropped as low as 1.2646 where it has found demand again. Now, it has tested and retested the broken uptrend line, trying to confirm its breakdown. Personally, I've drawn a downtrend line which represents an upside obstacle. As long as it stays below it, the GBP/USD pair could drop deeper.
GBP/USD trading conclusionThe 1.2646 immediate low represents a key downside obstacle. A drop below it activates more declines. This is seen as a selling opportunity.