Set 2 pending orders:
Buy GBP/USD at 1.6175 | SL at 1.61482 | TP at 1.6225
Sell GBP/USD at 1.61482 | SL at 1.6175 | TP at 1.60982
Use trailing stop of 15 pips for both orders.
Cancel the orders that didn’t hit (if any) by the end of the current session (UK or US).