What I also noticed was the prevalence of the 'commuter uniform', ie Hi viz jacket and helmet.
I've been wearing both for all of my commutes so far this year, but that's mostly because the helmet keeps my head warm and the
Altura Nightvision jacket is windproof but not lined / padded, so it's the most appropriate cycling jacket I've got.
Small Norm II hasn't been well, so it's been over a week since I cycled, but I'll just be in a t-shirt if the weather stays like it is today.
On the helmet thing, I wrote in the IAM survey that I wear it to protect me from myself, not from anyone else. If I have an accident on my own (clipless moment, tree branch, pot-hole etc) then a helmet
may help. If a car / van / truck / lorry is involved, though, it'll probably be of little use.