It's all good news!
The provider of the buttons didn't have a https address so, I saved a copy of the button to my server in the images directory. This is the cade I used in the end
Code:
<a href="http://www.ausscrapcentral.com.au/aschot50/in.php?id=27">
{if $smarty.server.SERVER_PORT == 443}
[img]{$ImagesDir}/top20.jpg[/img]
{else}
[img]http://www.ausscrapcentral.com.au/aschot50/button.php?id=27[/img]
{/if}
</a>
Thanks for all of your help its solved the problem perfectly.
Ian
Very Happy