The 'public_html' directory name should not appear in URLs (unless you have specifically created a new folder named 'public_html' inside your original 'public_html' directory.
Also, hard-coding the 'www' subdomain in the paths within your gallery's embedding code means that the gallery may not display on your main domain (without the 'www') due to the same-origin policy.
Use paths starting with a leading slash to denote your root directory and remove 'public_html' from the path names.
Try the following:

<!--START SIMPLEVIEWER EMBED.-->
<script type="text/javascript" src="/santino/SimpleViewer/svcore/js/simpleviewer.js"></script>
<script type="text/javascript">
    var flashvars={};
    flashvars.baseURL="/santino/SimpleViewer/";
    simpleviewer.ready(function () {
        simpleviewer.load("sv-container", "100%", "100%", “000000”, true, flashvars);
    });
</script>
<div id="sv-container"></div>
<!-- END SIMPLEVIEWER EMBED -->

The screenshot you posted does not seemt o correspond with what I see on your web server.
It looks like you should have a complete gallery folder here http://photo-passion.co.uk/santino/SimpleViewer/ (or possibly here http://photo-passion.co.uk/public_html/ … pleViewer/) but neither seems to exist.
Please check the files on your web server and if you continue to experience difficulties, please post the URL to the web page into which you are trying to embed the gallery so that I can take a look and help further.

Your gallery here http://photo-passion.co.uk/santino/SimpleViewer/ works fine now (but it didn't when I tried it earlier).
Now that it works, the embedding code I posted in my last post should work fine. If your gallery still does not display when using this embedding code, then try clearing your browser's cache before reloading your web page to ensure that your browser is fetching and using the most recent files from your web server.

One thing I should have mentioned earlier:

If you intend to manually embed your galleries into your WordPress posts (by uploading complete gallery folders and inserting embedding code into your WordPress posts), then there is no need to have installed WP-SimpleViewer. WP-SimpleViewer allows you to create galleries within the WordPress Dashboard and the plugin automatically handles the embedding code for you. Instructions for use can be found here.