Twenty Twelve Full Width custom page

Hi all,

I have created a page template in my child theme which is working fine, but I now want to make it full width. I have found this post which seems to point exactly what I want to do, however I cannot get this to work.

https://www.ads-software.com/support/topic/i-want-two-full-widthphp-templates-in-twentytwelve?replies=5

The code exert I am using is the 3rd post down by Drew Jaynes, and the issue I believe is my linking to the new ‘YOURS.php’ or my template name. I have added this code to my childs functions.php and placed the article page template in 3 locations, trying various different paths, but none of these seem to work:

twentytwelve/page-templates/article_page.php
twentytwelvechild/page-templates/article_page.php
twentytwelvechild/article_page.php

function childtheme_content_width() {
	if ( is_page_template( 'page-templates/article_page.php' ) ) {
		global $content_width;
		$content_width = 960; //Or whatever width you want
	}
}
add_action( 'template_redirect', 'childtheme_content_width' );

Obviously best practice would be to keep it in the child theme’s folder and in a similar directory to the twentytwelve as makes sense.

Site location of custom page showing issue https://coder-tronics.com/articles-2/

But how?

Many thanks,

Ant