OK I solved it by remembering something from very early Seafile versions. When you install it it does not create its own directory but installs its directories in whichever location you ran the installation script and that you have ownership of.
So, find conf directory (mine was in the user home directory) and in there find gunicorn.conf file and make sure this line reads like so:
# default localhost:8000
bind = "0.0.0.0:8000"
Restart seafile and seahub.
If you are going to move the seafile directories into their own location, make sure you edit the pids path in the gunicorn.conf to point to wherever you placed them.
V.