I hope someone can help as I'm struggling to work out what has changed with vncserver set up recently.
I used to be able to change the default vnc port from 5900 by using gconf-editor doing this:
Open up gconf-editor (Alt+F2, run gconf-editor).
• Browse to the key /desktop/gnome/remote_access/use_alternative_port and check the checkbox.
• Modify the value of the alternative_port key.
Unfortunately this value no longer appears in gconf-editor and all the posts I've found so far seem to be out of date as the solutions point to modifying files which no longer exist.