I have solved it
The problem lay with the Plan settings and had nothing to do with the menus. In the workflows for the relevant Plan the
URL for every login was set to display the userlist page instead of being blank as it should have been. Only by setting up a new plan and a new member in this user group (which worked as required) was I able to pinpoint that it must be something in the actual Plan that was causing the problem.
I have been able to unpublish the list and remove it from the menu for this user group which was the original requirement. I am grateful for your help, as it made me look very closely at *everything*!
Thank you