@timsoft
I missed the dnsmasq part and focused only on netbios/WINS, not knowing what name resolution was implemented for samba.
Flush the caches on your win10 and check with wireshark if/who and how is resolving toltest by looking at dns traffic:
https://wiki.wireshark.org/DNS
If it's on DNS, maybe follow EYo's advice.

I do have on the slack13.1 dnsmasq machine, but wins is not set up (mine is a small single subnet).
reports
which is the ip of the slack13.1 machine as one would expect.

following up an idea from EYo regarding dnsmasq i tried checking the dns records for my domain, and found a cname record for toltest.tree-of-life.co.uk pointing to a test mail server I was working on a while ago. As I set the local domain to tree-of-life.co.uk on my own slackware machines it looks like windows was querying toltest.tree-of-life.co.uk via netbios over tcp (and failing miserably because all windows networking is firewalled from the internet), instead of querying toltest. removing the cname entry and adding a (temporary) hosts entry on that machine for toltest.tree-of-life.co.uk (until the dns propogates to my isp).

The motto of this whole story is make sure your dns entries aren't the same as internal pc names if you want samba working with names, as windows 10 checks the fully qualified domain name in priority to the local netbios/host name on the samba server.

thanks very much for all the feedback and input from everyone who has contributed. I'll mark this solved. :-)

You only had DNS set for name resolution, no netbios/wins available on your domain master/local master slack13.1 machine. Happy to hear that you sorted it out now.
https://support.microsoft.com/en-us/...solution-order