I'm not sure it is to do with the Portal itself.
In overall_header.html, there are the following lines which seem to be at the centre of the problem:
<meta http-equiv="imagetoolbar" content="no" />
One of these points to more meta tags, one of which is the one showing <meta name="title" content="Portal" />
If someone can be kind enough to let me know where to look for the files that have the block of metadata that has this in it, I can solve the problem.