ignore this i worked it out!
tiredness is not my friend and it's been a while since I last looked at a webserver config
the solution is not to use suphp for this alias but to use modphp instead. My chrome seemed to cache the page longer ( even on full refresh ) than firefox and when I ran it in firefox I got a script error which indicated the ownership for the script was wrong. Seeing as multiple users can reference this app the solution is not to use suphp and use modphp or something else instead.
Options -Indexes +FollowSymLinks
AddType application/x-httpd-php .php .php3 .php4 .php5