Yes, Charlie, you're right. That'll teach me to post when away from an SME & rely on my (bad) memory.
Now that I'm back, I can't see a reference to proftpd anywhere in /etc/logrotate.conf - perhaps "thepair" could post the contents of theirs for comparison?
# see "man logrotate" for details
# rotate log files weekly
weekly
# keep 4 weeks worth of backlogs
rotate 4
# create new (empty) log files after rotating old ones
create
# uncomment this if you want your log files compressed
#compress
# RPM packages drop log rotation information into this directory
include /etc/logrotate.d
# no packages own wtmp -- we'll rotate them here
/var/log/wtmp {
monthly
create 0664 root utmp
rotate 1
}
# system-specific logs may be also be configured here.