Today's find a blue mug

I found 2 blue mugs today. I don't know anything about them but wondered if anyone else has any clues.

What causes or how was it made ? With the base having the circle in the centre. Does it mean it was in a mould or made on a potters  wheel?

They both have that dark spot under the base of the handle.

Potters mark J W L

Any help would be appreciated
Janice

Janice, the base is turned.

Otherwise I can't help.

Nice mug.