GBP/USD daily chart which illustrates the bearish swing between 1.6616 and 1.5232 reveals that the pair has strong resistance at 1.6085 which corresponds to 61.8% Fibonacci level.
Price level 1.6130, located slightly higher than 61.8% Fibonacci, has been acting as resistance each time when tested.
Thus, levels 1.6085-1.6130 are considered as a significant supply zone in the long-term and also as a good SELL entry for swing traders.
Yesterday we had bearish engulfing daily candlestick and daily closure below 1.5925 corresponding to 50% Fibonacci level which is bearish signal.

Yesterday we mentioned that 1.5985 is the key-level for the bulls so breakout below it allowed the pair to reach the 1.5875 level quickly.
After the GBP/USD pair has made bearish breakout below the depicted bullish channel, it is testing 1.5880 which is significant support level.
The bearish movement of yesterday renders 1.5965-1.5985 a good SELL entry for a possible mid-term bearish movement towards 1.5777.
Price levels 1.5965-1.5985 correspond to the backside of the broken channel and Fibonacci levels 50% and 61.8% of the latest bearish swing.
Break of 1.6060 invalidates the current bearish scenario.