Unfortunately, looks like I am going have to give up on this.
After a week of trying, it would appear that it is not possible for me to connect my UCS member server to a UCS primary domain controller and share folders to windows users without going in and restarting the smbd service every time a reboot happens.
This is a shame as it looked such a good solution. I have run out of ideas of things to try; so reluctantly I am moving on from UCS to try and find another solution.
For future reference by others this is the problem…
One PC configured with UCS as a AD domain controller. This works fine and provides all of the features and functionality expected. This is a small machine that is left on permanently.
Another PC with several large disks in it an only turned on when required. This has UCS installed and linked to the UCS domain as a member server. Windows-compatible member server is installed on this.
At first everything worked fine, then after the disks were mounted into /shares/… the server stopped allowing connections from windows machines after reboot. Restarting smbd after reboot fixes the problem, but only until the next reboot.