Please click on the photographs to see a larger view - they look rather dark here on the page.
As the fog swirled round, the frost visibly thickened - within a couple of hours of me noticing the fog, the garden was entirely white - like a modest covering of snow. As the night drew in and the temperatures dropped further, the frost thickened and you could see the air was full of ice crystals, twinkling as they caught the light. By midnight, there was a solid white covering over every surface, almost an inch thick.
And I mean every surface - when snow falls, even very gently, it only lands on uppermost surfaces - obviously as it's falling downwards. But this frosty covering wrapped around every surface of exposed items, in all dimensions and on the leading edge of larger structures like trees and furniture. By the time we were heading for bed, I put on an outside light to check progress and you could clearly see spiky crystals projecting randomly from the surfaces of leaves and garden furniture. I was hoping that it would last until daylight so that I could get some photographs - I had a new camera I was keen to give a good workout.
A little reading turned up some new information to me - it seems that if frost is formed specifically from fog freezing when it hits cold surfaces, it's called 'rime' - there's soft rime (very similar to hoar frost) and hard rime. I'd not heard that term before. I think this frost therefore must have been soft rime. Hoar frost is very similar, but forms when the relative humidity is just generally high and the moisture in the air freezes on surfaces. So it often occurs when there's a very cold snap after a period of thawing snow.
The moss on a dead tree I keep for my tree creeper - you can see how light and fluffy it is when it doesn't even disturb the tiny delicate seed heads of the moss and formed around them.
Unfortunately by sunrise, it must have warmed during the night and the crystals I'd seen as we shut up for the night had collapsed somewhat and now it just looked like a soft and gentle covering of very light powdery snow - and much of the frost on lower surfaces had seemingly dropped off, adding to the snowy appearance.
It was still beautiful nontheless and I was glad that I'd got to see it form during the evening, it was quite spectacular. As the sun rose, despite a very cool air temperature, its light texture ensured that it thawed very quickly where the sun hit it, remaining longer in shady areas. I got quite wet taking these photographs as it dripped off the trees. Some of the photographs were taken in my garden, some on a walk later in the morning.