Art Nouveau glazed ceramic flower pot / vase / jardiniere signed W or M

Hi everyone!
I have bought this beautiful pot in Sweden and I am very curious to know who made it, where and when.
I can't figure out the signature - is it just a W or M or is it something more complicated?
Besides the signature, there is only several printed numbers, no letters.
I am almost sure it is from the Art Nouveau period (it has this style plus the glazing has small cracks and it looks pretty old).
Any help would be appreciated!