Allow file expirary settings in php.ini ?

My HTML files are parsed for PHP, declared in .htaccess:

AddHandler application/x-httpd-php .html

Because my hosts default php.ini blocks a few things I want, I wrote a custom php.ini to override it -this is working well.

My File Expirary params are also set in .htaccess:

ExpiresActive On
ExpiresDefault A21600
ExpiresByType image/gif A2592000
ExpiresByType image/jpeg A2592000
<FilesMatch "^(error|forbidden)\.html$">
ExpiresDefault A0
</FilesMatch>

...but are not being passed into the HTTP header.

If I remove the PHP/HTML handler from my .htaccess, the expirary settings display in the HTTP header.
So I think my host's default php.ini is blocking it.


How do I allow/include expirary settings in my custom php.ini?
All I've seen is session/cookie expirary setting examples so far when I search.

Thanks.