Well Croydon is below London, but yes, there was plenty of mist and fog. Probably less than 100 yards visibility yesterday evening.
Still a fair amount in the morning, but it'd mostly listed this evening (though there was still reduced visibility, and it was quite thick in a few places).
I live above said demarcation and the fog is ultra-bad.
I had to drive to/from Northampton (curiously not in The North) twice this evening and I could barely see. Thank fuck I wasn't trying to land a Jumbo Jet!