Gallery Page with Pagination

<?php

class GalleryPage extends Page {

   public static $has_many = array(
    	'GalleryImages' => 'GalleryImage'
   );

   public static $defaults = array(
       'ItemsperPage' => '10',
       'ThumbnailImageWidth' => '100',
       'ThumbnailImageHeight' => '100',
       'FullImageWidth' => '800',
       'FullImageHeight' => '600',
   );

   public function getCMSFields() {

   	$fields = parent::getCMSFields();

	$gridFieldConfig = GridFieldConfig_RecordEditor::create();
	$gridFieldConfig->addComponent(new GridFieldBulkEditingTools());
	$gridFieldConfig->addComponent(new GridFieldBulkImageUpload());
	$gridFieldConfig->addComponent(new GridFieldSortableRows('SortOrder'));

	$gridfield = new GridField("GalleryImages", "Gallery Images", 	 	 	$this->GalleryImages()->sort("SortOrder"), $gridFieldConfig);

	$fields->addFieldToTab('Root.GalleryImages', $gridfield);

	return $fields;
  }
}

class GalleryPage_Controller extends Page_Controller {

	public static $allowed_actions = array (
	);

    public function Pagination() {
        // More info at http://doc.silverstripe.org/framework/en/howto/pagination
        $PaginatedList = new PaginatedList($this->data()->Images(), $this->request);
        $PaginatedList -> setPagelength(10);
        return $PaginatedList;
    }

	public function getGalleryImages() {
		return $this->GalleryImages()->sort("SortOrder");
	}
	public function init() {
		parent::init();
	}

}