public function getCMSFields() {
		$fields = parent::getCMSFields();

		$previewField = new LiteralField("SecureImageFull",
				"<img id='thumbnailImage' class='thumbnail-preview' src='".$this->Link()."' alt='Secured File' />\n"
		);

		$url = $this->Link();// 5 minute link expire
		$link = ReadonlyField::create('CDNUrl', 'CDN reference',  $this->CDNFile);

		$link->dontEscape = true;

		if ($top = $fields->fieldByName('Root.Main.FilePreview')) {
			$field = $top->fieldByName('FilePreviewImage');
			$field->insertBefore($previewField, 'ImageFull');
			$field->removeByName('ImageFull');
			$top->replaceField('CDNUrl', $link);
		}

		return $fields;
	}