http://domain/phpmyadmin login page not loading - error 403 forbidden
Default Ubuntu 18.04 server added nginx & php using apt-get
Installed the latest version of phpmyadmin manually to avoid bug in the 18.04 release. (https://stackoverflow.com/questions/48001569/phpmyadmin-count-parameter-must-be-an-array-or-an-object-that-implements-co/48682873#48682873)
http:/domain/index.php worked fine and from there other php pages would load, via the website menu, so I assumed php was working correctly. A php page with phpinfo(); worked as expected.
I had just done the setup on an identical server without a problem. What had I forgotten? As phpmyadin was outside the /var/www/html folder I thought it was a folders permissions issue.