is_page() used to disable header image not working on FireFox

<?php
// Check to see if the header image has been removed - added the is_page condition
	if( !is_page('photos' ) :
	$header_image = get_header_image();
	if ( !empty( $header_image ) ) :
?>
[...]
<?php endif; // end check for removed header image ?>
<?php endif; // end check for photos page ?>

Thanks – I tried, couldn’t figure out where to add the endifs, kept getting syntax error.
My code is here, https://pastebin.com/3h2b1kcV – where should I add the two endifs?
No coding expert.

https://pastebin.com/14K3hGnS

I get a syntax error after pasting your code
https://pastebin.com/7m2xTzMF

Typo! Change:

if( !is_page('photos' ) : // check for photos page

to:

if( !is_page('photos' ) ) : // check for photos page

Sorry: no syntax error, but the header image on https://www.thetwobyres.co.uk/photos is still enabled in FireFox.

Must have been the cache – now it seems to work in all browsers.
Thanks for helping me out!