My trading setup would begin around 1.41, anything below would signal an even further drop towards 1.40 and below, anything above 1.42 and there may be an upward trend. Regardless I'm keeping a close eye on the psychological level of 1.41. When a Brexit indeed does happen, we can expect to see an even much lower GBP/USD, perhaps even as low as 1.25 in the short term. I'm usually a cautious fx trader, but in this case I'd risk a 30 pip SL in either direction.
We'll see what happens.