This is silly.... most of the world didn't live in england.

All cultures (including mine), have a way to warn kids, or adults for not to stay too long in the sun. From normal sunburn, to feeling light-headenes/fainting due to heat excaustion, etc.

In the winter was the opposite. (stay in the sun to get some sunlight and not get sick).

So, they knew, and had nothing to do with 'class'. Also, they knew some sun was good/beneficial, especially during the winter.