The rising trendline and the horizontal support at the FX:GBPUSD has been broken. Price is trying to retrace, but is unable to cross back the upside. If price does cross above, it should face resistance again at the red line.
Short can be initiated at CMP or at 1.2535 if price retraces again later, if you are late to see this.
Target will be a little above the next support level: 1.2424
Stop little above the red resistance: 1.2593