Ah, another weekend and another foray into troubleshooting issues with my recently acquired Blacknight hosting. For the past few weeks I had been using PHP4 but decided today that I should really move to PHP5 for my new personal project.
After some head scratching, it seems that I can not override the display_errors setting in the pho.ini file for PHP5 which by default is set to Off via the .htaccess file though I can do this for PHP4. However, I can override it by using ini_set() within my scripts.
This information might come in handy for some other poor soul wondering why they were getting blank screens. I will have to investigate at some point what options I have for overriding other settings as it is nice to keep all these things centralised.