There is nothing unusual in this log. The entries for opening and closing a connection from localhost are from the script that checks if proftpd is running.
Code: Jun 14 23:30:01 vps.axoc.co.uk proftpd[13524] vps.axoc.co.uk (127.0.0.1[127.0.0.1]): FTP session closed. Jun 14 23:59:03 vps.axoc.co.uk proftpd[24503] vps.axoc.co.uk: ProFTPD killed (signal 15) Someone did... 29 minutes later
This is done by an ISPConfig cron job which is needed for the FTP traffic accounting. Nothing to worry about.