Cable rebound is part of a sag in the US dollar
It's not so much that the pound is gaining in the past few hours, it's more than the US dollar is under some pressure.
Cable is now down just 12 pips on the day to 1.2858 from a low of 1.2811. Much of the move came about an hour ago in a 30 pip rally from 1.2825. That was sparked by a report that the EU is exploring an Irish border backstop that could help May win approval for her Brexit plan.
The report says EU officials are exploring a border deal that would be more palatable to the UK.
Here's a 10 minute chart starting after last Wednesday's peak. It's a big hill to climb to a close above 1.2850/60 would be a good start.