Thanks John,
I did have a problem back in February of this year that required a full clean-up and the site is now scanned daily by several security scanners, so this is probably a hang-over from the problem back earlier this year.
As a result of some of the posts on this and the other forum, I have also installed ZB Block, which adds another layer of security.
That said, I am paranoid, so if you, or anybody else encounters any other problem, do please let me know, there are a lot of terrible invaders out there.
best regards
Steve