Lidded jar help please. - James Mounter, Callander?

A small, but heavy for it's size, lidded jar with slip decoration, seems very well made and clear, but unknown, to me, initials on the base.

Having now come across a couple of very similar pots, jar the same but different decoration, I believe this may be by James Mounter, Callander, Scotland; the other pots were marked with a ink stamp: Mounter Pottery Callander.

The initials fit as far as the J & M are concerned but there is nothing to suggest that this pottery still exists so at present I can check no further.

Paul

Another one here -

https://www.20thcenturyforum.com/t15966-slipware-lidded-pot-signed-jfm#123981

And another one

https://www.20thcenturyforum.com/t16103-slip-ware-teapot-marked-jem-or-tem

Now we just need the cup & saucer.