Solved this myself, but was a pain so thought I'd share the knowledge,
in public function draw()
$id = $item->getProductid(); $objectManager = \Magento\Framework\App\ObjectManager::getInstance(); $product = $objectManager->get('Magento\Catalog\Model\Product')->load($id); $brand = $product->getAttributeText('manufacturer');
manufacturer to whatever custom attribute code you want.
Quick and dirty - yes I know its a mod of core code and will translate to my own module now it's working, but hope this makes others life easier.