Runway Blog Title (layout variables)

Hi,

I've got an issue with a site whereby the blog Title isn't being pulled through on the post page. I'm using layout variables to display them in the header. I will try and be as succinct as I can with my snippets:

global.header:

    <?php 
        if (perch_layout_var('meta', true)) {
            echo perch_layout_var('meta', true);
        } else {
            perch_page_attributes();
        }
    ?>

post.php

<?php 
    $post_slug = perch_get('year').'/'.perch_get('month').'/'.perch_get('s');
    perch_layout('global/header', array(
        'meta'  => perch_blog_custom(array(
                'template' => 'blog/meta.html',
                'filter' => 'postSlug',
                'match' => 'eq',
                'value' => $post_slug,
            ), true),
        ));
?>

blog/meta.html layout

<title><perch:blog id="meta_title" type="textarea" label="Meta Title" size="xs" escape="true" count="chars" /></title>
<meta name="description" content="<perch:blog id="meta_description" type="textarea" label="Meta Description" size="xs" escape="true" count="chars" />" />
<meta name="keywords" content="<perch:blog id="meta_keywords" type="textarea" label="Meta Keywords" size="xs" count="chars" />" />

post.html template

<perch:blog id="meta_title" type="textarea" label="Meta Title" suppress="true" order="4" size="xs" escape="true" />
<perch:blog id="meta_description" type="textarea" label="Meta Description" suppress="true" order="5" size="xs" escape="true" />
<perch:blog id="meta_keywords" type="textarea" label="Meta Keywords" suppress="true" order="6" size="xs" />

Diagnostics

Perch Runway: 2.8.8, PHP: 5.6.8, MySQL: mysqlnd 5.0.11-dev - 20120503 - $Id: 3c688b6bbc30d36af3ac34fdd4b7b5b787fe5555 $, with PDO
Server OS: Linux, cgi-fcgi
Installed apps: content (2.8.8), assets (2.8.8), categories (2.8.8), perch_blog (4.6), perch_forms (1.8.3), perch_mailchimp (2.0.1), perch_twitter (3.5.1)
App runtimes: <?php $apps_list = array( 'content', 'categories', 'perch_blog', 'perch_forms', 'perch_mailchimp', 'perch_twitter' );
PERCH_LOGINPATH: /perch
PERCH_PATH: xxxx/public_html/perch
PERCH_CORE: xxxx/public_html/perch/core
PERCH_RESFILEPATH: /var/sites/w/whatthefoot.co.uk/public_html/perch/resources
Image manipulation: GD
PHP limits: Max upload 100M, Max POST 100M, Memory: 128M, Total max file upload: 100M
Resource folder writeable: Yes
DOCUMENT_ROOT: xxxx/public_html
HTTP_HOST: www.whatthefoot.co.uk
REQUEST_URI: /perch/core/settings/diagnostics/
SCRIPT_NAME: /perch/core/settings/diagnostics/index.php