Thanks very much. You were quite right. The passwd file showed it was pointing at a directory /srv/ftp. I put a file in /srv/ftp and it is working fine.
I shall change it point to a data directory.
I had not noticed the /srv directory before and all my server software is installed in various places around the system at the whim of the rpm packages. I think a tidy up is called for!
Thanks also for the security tips. In fact I am only running anonymously on my internal network, my plan is to have proper login for all users before I go live on the internet.