Clothes not always related to weather conditions!

So recently I visited Cardiff. It was really important trip as I attended to an Open Day at University of South Wales.
That was my second time I have visited Britain. And for the second time I have noticed something quite interesting to me.
In Wales climate is rather mild, but when we've arrived it was freezing.
Fortunately I was prepared for that. But I was the only one.
On the first day I spotted many people wearing shorts and sandals, walking on the streets without even light jacket on!
Maybe there is something wrong with me, but it is not very usual view.
When I was in Spain everyone were wearing thick sweaters even though it was about 20 degrees. So, I connected that memory with the climate differences and facing Welsh people clothing was funny experience.
What do you guys think about that? Is it normal to wear shorts in wintertime? :)

                         

In the picture, you can see a woman wearing sandals on the 22nd November. Before I took that photo I've seen some white frost on the roofs, so believe me, it was cold!