lawrencebrown

I found a resolution:

<?php
$temp = $wp_query;
$wp_query= null;
$wp_query = new WP_Query();
$newID = get_post_meta($post->ID, 'catID', true);
$wp_query->query('cat='.$newID.'&showposts=10'.'&paged='.$paged);
?>

So this allows you to put just the ID number of a cat into a custom field and it will create a loop for you in that custom page.

Turns out it was a plug-in that needed updating. Remember if you are getting strange results to try your site without the plugins and manually check the plugin author site as they may have not pinged wordpress with the update!