Displaying Custom Fields With NextGen Gallery Albums

I have a site (on my local dev server) that uses NextGen galleries. The client wants to add links on pages created for these galleries (using manage gallery > create new page) to other sites and I have added a custom field for this:

<?php $gallery_link = get_post_meta($post->ID, 'Gallery_Link', true);
	if ($gallery_link) {
	?>
       <a href="<?php echo $gallery_link; ?>" target="_blank">See more images and buy prints on this website</a>.
<?php } else { ?>
<p><a href="contact">Contact me</a> if you are interested in buying prints.</p>
<?php } ?>

This works and the client can add his URLs and they display as intended.

However, I want to use the NextGen album feature and have built a new all galleries template and added the [album id=1 template=extend] shortcode. Galleries load as expected, but I can’t get the custom fields to display on my page when viewing the individual galleries. I have tried adding various code to my template, the latest being this:

<?php // second loop for gallery urls
	global $wp_query;
	$gallery_link = $wp_query->post->ID;
	echo get_post_meta($gallery_link, 'Gallery_Link', true);
	wp_reset_query();
?>

Sorry if this is a long explanation, but I have exhausted my own resources on this one and am frustrated by a long afternoon with no success! (I tried the NGG Custom Fields plugin but that doesn’t do it either.)