Varnish cache backend won't clear the cache programaticly when Varnish Cache Clearing is set to none

This module is exactly what I need. I am unable to test it properly though.

I have Varnish(2.1.4) & Memcache(1.4.5).

I have used page cache set to Varnish in settings.php:

$conf['cache_backends'] = array('sites/all/modules/contrib/varnish/varnish.cache.inc');
$conf['cache_class_cache_page'] = 'VarnishCache';
$conf['cache'] = 1;
$conf['cache_lifetime'] = 0;
$conf['page_cache_maximum_age'] = 21600;

I also have setup memcache and assigned other bins to memcache clusters.

I created this rule to clear cache_page when an 'article' node is updated:

{ "rules_cache_clear_article_update" : {
    "LABEL" : "Cache clear on article update",
    "PLUGIN" : "reaction rule",
    "REQUIRES" : [ "rules", "cache_actions" ],
    "ON" : [ "node_update" ],
    "IF" : [
      { "node_is_of_type" : { "node" : [ "node" ], "type" : { "value" : { "article" : "article" } } } }
    ],
    "DO" : [
      { "cache_actions_action_clear_cache" : { "tables" : { "value" : { "cache_page" : "cache_page" } } } }
    ]
  }
}

However, after editing the title of an article node, the cache_page bin is not flushed. I was expecting Varnish to have purged completely. But I still see HITs for pages as an anonymous user after this. Am I testing this correctly?