Further to last :-
As I was on my local machine I followed some advice and added
disable_strict_mode.cnf
containing
[mysqld]
sql_mode=IGNORE_SPACE,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION
to the /etc/mysql/conf.d/ folder
this allowed the registered user to upload.
I can't work out where the difference is between the admin and the registered user SQL settings in UPLOAD.PHP that would bar the reg user and not the admin by strict mode.
I would have thought it would be both or neither.