Cable shorts square up ahead of the Fed
GBP shorts are the most-crowded speculative trade in FX (maybe anywhere).
At the moment, GBP/USD is on a nice run up to 1.2217 from 1.2170 a couple hours ago. The run looks like profit-taking on shorts to me, along with a bit of technical buying.
I can see the argument for clearing out of speculative shorts with so much Fed risk to come. There is also increasing talk about how Boris Johnson has boxed himself into an spot that's impossible to get out of, but I don't think that's anything new.