I remember that evening, many airfields in the UK went out in fog very quickly. I think this was the same day, earlier on, when a twin going into Elstree became disorientated in shallow fog and hit the ground hard and bounced into the air again. It diverted to Luton whilst we had the emergency services standing by.
The tragedy of Graham Hill was that at the time of the accident Luton was clear but went out in fog later. Still, no use going over old ground.