<!-- Query - 1 post from each category no duplication -->
<?php $do_not_duplicate = array();
<!-- Featured is first -->
<?php $my_query = new WP_Query('category_name=featured&posts_per_page=1');
while ($my_query->have_posts()) : $my_query->the_post();
$do_not_duplicate[] = $post->ID; ?>
<?php
// Get the ID of a given category
$category_id = get_cat_ID( 'Featured' );
// Get the URL of this category
$category_link = get_category_link( $category_id );
?>
<article>
<header>
<h1><a href="<?php echo esc_url( $category_link ); ?>">// Featured</a></h1>
</header>
<div class="related-thumb">
<a href="<?php the_permalink() ?>" rel="bookmark"><?php the_post_thumbnail( 'cat-post-thumb'); ?></a>
</div>
<h2><a href="<?php the_permalink() ?>" rel="bookmark"><?php the_title(); ?></a></h2>
<time datetime="<?php echo the_time('j-m-Y'); ?>" pubdate><?php echo ''.get_the_time('j').' '.''.get_the_time('M').' '.get_the_time('Y').''; ?></time>
<p><?php the_excerpt(); ?></p>
</article>
<?php endwhile; ?>
<!-- Top 3 -->
<?php $my_query = new WP_Query(array('category_name' => 'top-three', 'posts_per_page' =>1, 'post__not_in' => $do_not_duplicate));
while ($my_query->have_posts()) : $my_query->the_post();
$do_not_duplicate[] = $post->ID; ?>
<?php
// Get the ID of a given category
$category_id = get_cat_ID( 'top-three' );
// Get the URL of this category
$category_link = get_category_link( $category_id );
?>
<article class="centre-margin">
<header>
<h1><a href="<?php echo esc_url( $category_link ); ?>">// Top Three</a></h1>
</header>
<div class="related-thumb">
<a href="<?php the_permalink() ?>" rel="bookmark"><?php the_post_thumbnail( 'cat-post-thumb'); ?></a>
</div>
<h2><a href="<?php the_permalink() ?>" rel="bookmark"><?php the_title(); ?></a></h2>
<time datetime="<?php echo the_time('j-m-Y'); ?>" pubdate><?php echo ''.get_the_time('j').' '.''.get_the_time('M').' '.get_the_time('Y').''; ?></time>
<p><?php the_excerpt(); ?></p>
</article>
<?php endwhile; ?>
<!-- Arts -->
<?php $my_query = new WP_Query(array('category_name' => 'arts', 'posts_per_page' => 1, 'post__not_in' => $do_not_duplicate));
while ($my_query->have_posts()) : $my_query->the_post();
$do_not_duplicate[] = $post->ID; ?>
<?php
// Get the ID of a given category
$category_id = get_cat_ID( 'Arts' );
and so on