Perhaps that's what happened at Camborne - the fog was within
1000m but wasn't at the station - adjacent fog should have been reported.

I think that's almost certainly the case. The Camborne site is around 2000m from an area of the north coast very prone to sea fog.

As for the 09:00 reporting time, whilst it many cases inland the fog has gone by then, on the coast it's often brought in by the sea breeze, so in summer the fog risk is higher later in the day.

There's an excellent photo of the onset of a north coast sea breeze causing a fog roller here, just passing Lands End. (Moving right to left) associated with the early afternoon onset of the north coast sea breeze. 5th Aug 2018

http://www.turnstone-cottage.co.uk/fog.html


Graham
Penzance