Apologies if this has been asked before, I have searched for an answer but perhaps aren't quite using the correct terminology.
I have inherited a WordPress site that uses a custom theme. Within the theme, many pages reference page templates such as "Charity_Temp_Nov13" or "Search_03".
If I change the Wordpress site theme to a new one, what happens to the references to these page templates when the pages are loaded? Does Wordpress apply no theme, and just display the page content anyway, or is an error thrown, for example?
Just to avoid "suck it and see" answers, I currently do not have an offline environment to test this (its in progress but the site is 4GB in size), and the client won't entertain down time. Therefore I'm looking for authoritative answers before testing can begin