I should have added the findus.php file in the includes/extra_datafiles directory simply contains:-

PHP Code:
define(FILENAME_FINDUS, 'findus'); 
The above is as per the wiki guide, however as the constant FILENAME_DEFINE_FINDUS is used in the header.php file I also altered the FILENAME_FINDUS constant to read FILENAME_DEFINE_FINDUS, the difference when I changed this was I got a 404 error rather than simply no content.