Reinis thanks very much for your response. The owner shown for : /var/run/php/php7.0-fpm.sock is 33 & group is 33. Both have read/write access but other groups have no access rights.

I therefore added the following line at the beginning of nginx.conf

user 33 33;

However when I tried to restart nginx it failed and systemctl status says that getpwnam("33") failed. What have I done wrong here?

Thanks for your continued help.