Great Britain has not left the EU.
No changes have been made to the treaties, and when the changes are eventually negotiated, very little in the way of trading arrangements will be altered.
However, after the referendum went the wrong way, British and European leaders hopped around like headless chickens, and capitalists pulled massive amounts out of the British economy. So the GBP (blue graph), instead of bouncing back as I had expected, continued to fall until now. There are signs that it has hit a bottom at last. It remains to be seen if it will make a recovery of any significance.
Meanwhile, the Euro (amber graph) continues is upward trend.