diff --git a/includes/block-override-functions.php b/includes/block-override-functions.php
index a2a6b0a..2ca503f 100644
--- a/includes/block-override-functions.php
+++ b/includes/block-override-functions.php
@@ -3,6 +3,8 @@
  * Implements common functions used in block overrides
  *
  */
+require_once __DIR__ . '/class-block-recursion-control.php';
+
 
 /**
  * Overrides a core block's render_callback method, if required.
@@ -26,40 +28,15 @@ function fizzie_maybe_override_block( $args, $blockname, $render_callback ) {
     return $args;
 }
 
-
 /**
  * Determines whether or not to process this content.
  *
  * @param string|integer Unique ID for the content
  * @return bool - true if the post has not been processed. false otherwise
  */
-function fizzie_process_this_content( $id  ) {
-    global $fizzie_processed_content;
-    // Use this rather than context['postId']
-    global $post;
-    $fizzie_processed = bw_array_get( $fizzie_processed_content, $id, false );
-
-    /*
-    if ( empty( $fizzie_processed_content ) ) {
-        $global_id = isset( $post ) ? $post->ID : null;
-        if ( $global_id ) {
-            $fizzie_processed_content[ $global_id ] = $global_id;
-        }
-    }
-    */
-
-
-    if ( !$fizzie_processed ) {
-        $fizzie_processed_content[$id] = $id ;
-    }
-
-    /** Stop when it looks highly likely we've missed something */
-    if ( count( $fizzie_processed_content ) > 10 ) {
-        $fizzie_processed = true;
-
-    }
-    bw_trace2( $fizzie_processed_content, "processed posts", true, BW_TRACE_DEBUG );
-    return( !$fizzie_processed );
+function fizzie_process_this_content( $id ) {
+    $recursion_control = Fizzie_Block_Recursion_Control::get_instance();
+    return $recursion_control->process_this_content( $id );
 }
 
 /**
@@ -74,15 +51,12 @@ function fizzie_process_this_content( $id  ) {
  * - core/block - possibly
  *
  * Note: The top level is within the template, which loads the template parts and/or queries.
+ *
+ * @param string|integer $id
  */
 function fizzie_clear_processed_content( $id=null ) {
-    global $fizzie_processed_content;
-    if ( $id ) {
-        array_pop( $fizzie_processed_content );
-    } else {
-        $fizzie_processed_content = array();
-    }
-    bw_trace2( $fizzie_processed_content, "cleared", false, BW_TRACE_DEBUG );
+    $recursion_control = Fizzie_Block_Recursion_Control::get_instance();
+    $recursion_control->clear_processed_content( $id );
 }
 
 /**
@@ -92,102 +66,11 @@ function fizzie_clear_processed_content( $id=null ) {
  *
  * @param $id string|integer recursive ID detected
  * @param $type string content type
- * @return string
+ * @return string HTML reporting the error to the user
  */
 function fizzie_report_recursion_error( $id, $type='core/post-content') {
-    bw_trace2();
-    bw_backtrace();
-    global $bad_id, $bad_fizzie_processed_content, $fizzie_processed_content;
-    $bad_id = $id;
-    $bad_fizzie_processed_content = $fizzie_processed_content;
-
-    $content = array();
-    $content[] = '<div class="recursion-error">';
-    switch ( $type ) {
-        case 'core/post-content':
-            $content[] = __( 'Content not available; already processed.', 'fizzie' );
-            break;
-        case 'core/template-part':
-            $content[] = __( 'Template part not processed to avoid infinite recursion', 'fizzie');
-            break;
-        case 'core/block':
-            $content[] = __( 'Reusable block not processed to avoid infinite recursion', 'fizzie');
-            fizzie_add_filter_rest_prepare_wp_block();
-            break;
-        default:
-            $content[] = __( 'Infinite recursion error prevented', 'fizzie');
-    }
-    if ( defined( 'WP_DEBUG' ) && WP_DEBUG ) {
-        $content[] = "<span class=\"recursion-error-context $type\">";
-        $content[] = '<br />';
-        $content[] = $id;
-        $content[] = '<br />';
-        $content[] = $type;
-        $content[] = '<br />';
-        global $fizzie_processed_content;
-        $content[] = implode( ',', $fizzie_processed_content );
-        $content[] = '</span>';
-    }
-    $content[] = '</div>';
-    $content = implode( " \n", $content);
-    return $content;
-}
-
-function fizzie_add_filter_rest_prepare_wp_block() {
-    // We only need to do this in REST API processing
-    // But this will only be called in REST API processing
-    // So no need to check
-    add_filter('rest_prepare_wp_block', 'fizzie_rest_prepare_wp_block', 10, 3);
+    $recursion_control = Fizzie_Block_Recursion_Control::get_instance();
+    $html = $recursion_control->report_recursion_error($id, $type);
+    return $html;
 }
 
-/**
- *
- * Fiddle with the raw content to remove the wp:block block.
- *
- * [raw] => <!-- wp:paragraph -->
-<p>This is reusable block 21117</p>
-<!-- /wp:paragraph -->
-
-<!-- wp:block {"ref":1134} /-->
- * @param $response
- * @param $post
- * @param $request
- * @return mixed#
- */
-function fizzie_rest_prepare_wp_block( $response, $post, $request ) {
-    bw_trace2();
-    bw_backtrace();
-    global $bad_id;
-    global $bad_fizzie_processed_content;
-    $content = $response->data['content']['raw'];
-    $content = fizzie_replace_bad( $content, $bad_id );
-    foreach ( $bad_fizzie_processed_content as $id ) {
-        $content = fizzie_replace_bad( $content, $id );
-    }
-    // Convert any remaining to a missing block
-    $content = str_replace( "wp:block {", "missing {", $content );
-
-    $response->data['content']['raw'] = $content;
-    bw_trace2(  $response, "response", false );
-    return $response;
-}
-
-function fizzie_replace_bad( $content, $bad_id ) {
-    $replacement_block = "<!-- wp:paragraph -->";
-    $replacement_block .= sprintf(__('Error: Recursion was detected while loading the reusable block with post ID %1$s. '), $bad_id);
-    $replacement_block .= fizzie_title_link($bad_id);
-    $replacement_block .= '<br />';
-    $replacement_block .= "Recommendation: Please delete this block.";
-    $replacement_block .= "<!-- /wp:paragraph -->";
-    $content = str_replace("<!-- wp:block {\"ref\":$bad_id} /-->", $replacement_block, $content);
-    return $content;
-}
-
-
-function fizzie_title_link( $id  ) {
-    $link = sprintf( '<a href="%s">%s</a>', esc_url( get_permalink( $id ) ), esc_html( get_the_title( $id ) ) );
-    return $link;
-}
-
-
-
diff --git a/includes/block-overrides.php b/includes/block-overrides.php
index 05f19ac..4d52f4d 100644
--- a/includes/block-overrides.php
+++ b/includes/block-overrides.php
@@ -4,13 +4,14 @@
  *
  */
 require_once __DIR__ . '/block-override-functions.php';
+require_once __DIR__ . '/class-block-recursion-control.php';
 
 /**
  * Here we include the blocks we want to override.
  *
  * Either comment out the ones that aren't needed any more - when Gutenberg/core's
  * satisfies the requirement
- * or find another way of automatically determining whether or not to include the file.
+ * or find another way to automatically determine whether or not to include the file.
  */
 require_once __DIR__ . '/query-pagination.php';
 require_once __DIR__ . '/query-loop.php';
@@ -27,7 +28,6 @@
  */
 add_filter( 'register_block_type_args', 'fizzie_register_block_type_args', 9 );
 
-
 /**
  * Implements overrides for core blocks which we need to improve.
  *
diff --git a/includes/class-block-recursion-control.php b/includes/class-block-recursion-control.php
new file mode 100644
index 0000000..52acf25
--- /dev/null
+++ b/includes/class-block-recursion-control.php
@@ -0,0 +1,223 @@
+<?php
+
+/**
+ * Class Fizzie_Block_Recursion_Control
+ *
+ * Implements the recursion control functions in an extendable class
+ * Blocks use the public API passing the unique ID for their block.
+ *
+ * - fizzie_process_this_content( $id )
+ * - fizzie_clear_processed_content( $id )
+ * - fizzie_report_recursion_error( $id )
+ *
+ * These functions will be implemented by methods
+ * accessed using Fizzie_Block_Recursion_Control::get_instance
+ */
+
+
+class Fizzie_Block_Recursion_Control {
+
+    /**
+     * Stack of recursive blocks unique keys.
+     *
+     * @var array
+     *
+     */
+    public $processed_content = [];
+
+    /**
+     * Bad $id where recursion was detected.
+     */
+    public $bad_id;
+    /**
+     * Call stack when recursion was detected.
+     * @var
+     */
+    public $bad_processed_content;
+
+    /**
+     * Container for the main instance of the class.
+     *
+     * @var Fizzie_Block_Recursion_Control|null
+     */
+    private static $instance = null;
+
+    /**
+     * Utility method to retrieve the main instance of the class.
+     *
+     * The instance will be created if it does not exist yet.
+     *
+     * @since
+     *
+     * @return Fizzie_Block_Recursion_Control The main instance.
+     */
+    public static function get_instance() {
+        if ( null === self::$instance ) {
+            self::$instance = new self();
+        }
+
+        return self::$instance;
+    }
+
+    /**
+     * Determines whether or not to process this content.
+     *
+     * @param string|integer Unique ID for the content
+     * @return bool - true if the post has not been processed. false otherwise
+     */
+    function process_this_content( $id  ) {
+        $processed = isset( $this->processed_content[ $id ] );
+        if ( !$processed ) {
+            $this->processed_content[$id] = $id ;
+        }
+
+        /** Stop when it looks highly likely we've missed something */
+        if ( count( $this->processed_content ) > 10 ) {
+            $processed = true;
+
+        }
+        bw_trace2( $this->processed_content, "processed posts", true, BW_TRACE_DEBUG );
+        return( !$processed );
+    }
+
+    /**
+     * Pops or clears the array of processed content.
+     *
+     * As we return to the previous level we can clear the processed content.
+     * Basically this is something we have to do while processing certain inner blocks:
+     *
+     * - core/post-content
+     * - core/template-part
+     * - core/post-excerpt - possibly
+     * - core/block - possibly
+     *
+     * Note: The top level is within the template, which loads the template parts and/or queries.
+     */
+    function clear_processed_content( $id=null ) {
+        if ( $id ) {
+            array_pop( $this->processed_content );
+        } else {
+            $this->processed_content = array();
+        }
+        bw_trace2( $this->processed_content, "cleared", false, BW_TRACE_DEBUG );
+    }
+
+    /**
+     * Reports a recursion error to the user.
+     *
+     * If WP_DEBUG is true then additional information is displayed.
+     *
+     * @param $id string|integer recursive ID detected
+     * @param $type string content type
+     * @return string
+     */
+    function report_recursion_error( $id, $type='core/post-content') {
+        bw_trace2();
+        bw_backtrace();
+
+        $this->bad_id = $id;
+        $this->bad_processed_content = $this->processed_content;
+        // $content = $this->create_basic_error();
+
+        $content = array();
+        $content[] = '<div class="recursion-error">';
+        switch ( $type ) {
+            case 'core/post-content':
+                $content[] = __( 'Content not available; already processed.', 'fizzie' );
+                break;
+            case 'core/template-part':
+                $content[] = __( 'Template part not processed to avoid infinite recursion', 'fizzie');
+                break;
+            case 'core/block':
+                $content[] = __( 'Reusable block not processed to avoid infinite recursion', 'fizzie');
+                $this->add_filter_rest_prepare_wp_block();
+                break;
+            default:
+                $content[] = __( 'Infinite recursion error prevented', 'fizzie');
+        }
+        if ( defined( 'WP_DEBUG' ) && WP_DEBUG ) {
+            $content[] = "<span class=\"recursion-error-context $type\">";
+            $content[] = '<br />';
+            $content[] = $id;
+            $content[] = '<br />';
+            $content[] = $type;
+            $content[] = '<br />';
+
+            $content[] = implode( ',', $this->processed_content );
+            $content[] = '</span>';
+        }
+        $content[] = '</div>';
+        $content = implode( " \n", $content);
+        return $content;
+    }
+
+    /**
+     * Adds a filter hook to alter the response for wp_block.
+     *
+     * There's no need to check if it is REST API processing.
+     * The hook function won't get called if it isn't.
+     */
+    function add_filter_rest_prepare_wp_block() {
+        add_filter( 'rest_prepare_wp_block', [ $this, 'rest_prepare_wp_block' ], 10, 3 );
+    }
+
+    /**
+     * Fiddles with the raw content to remove `wp:block` blocks.
+     * `
+     * [raw] => <!-- wp:paragraph -->
+     * <p>This is reusable block 21117</p>
+     * <!-- /wp:paragraph -->
+     * <!-- wp:block {"ref":1134} /-->
+     * `
+     * @param $response
+     * @param $post
+     * @param $request
+     * @return mixed
+     */
+    function rest_prepare_wp_block( $response, $post, $request ) {
+        bw_trace2();
+        bw_backtrace();
+
+        $content = $response->data['content']['raw'];
+        $content = $this->replace_bad( $content, $this->bad_id );
+        foreach ( $this->processed_content as $id ) {
+            $content = $this->replace_bad( $content, $id );
+        }
+        // Convert any remaining `wp:block` values to a `missing` block.
+        $content = str_replace( "wp:block {", "missing {", $content );
+
+        $response->data['content']['raw'] = $content;
+        bw_trace2(  $response, "response", false );
+        return $response;
+    }
+
+    /**
+     * Replaces wp:block for ref:bad_id with a paragraph.
+     *
+     * @param $content
+     * @param $bad_id
+     * @return string|string[]
+     */
+    function replace_bad( $content, $bad_id ) {
+        $replacement_block = "<!-- wp:paragraph -->";
+        $replacement_block .= sprintf(__('Error: Recursion was detected while loading the reusable block with post ID %1$s. '), $bad_id);
+        $replacement_block .= $this->title_link($bad_id);
+        $replacement_block .= '<br />';
+        $replacement_block .= "Recommendation: Please delete this block.";
+        $replacement_block .= "<!-- /wp:paragraph -->";
+        $content = str_replace("<!-- wp:block {\"ref\":$bad_id} /-->", $replacement_block, $content);
+        return $content;
+    }
+
+    /**
+     * Returns a title link to the post.
+     *
+     * @param integer $id Post ID.
+     * @return string HTML title link.
+     */
+    function title_link( $id  ) {
+        $link = sprintf( '<a href="%s">%s</a>', esc_url( get_permalink( $id ) ), esc_html( get_the_title( $id ) ) );
+        return $link;
+    }
+
+}
\ No newline at end of file