Thanks both, that is definitely what's happing, as like bigsy I have an account with Zen. So the answer to my question is no there is no simple way of making my ports stealth . Project abandoned.
I tried adding rules to see if they would make any difference which they did not so I will remove them. The implicit deny rule I have added would stop anything internally using those ports anyway.
I put an extra implicit deny rule in to monitor any network activity I was not expecting. I presume like most firewalls I have worked on there is an invisible deny rule anyway.
Thanks for the help