Magento Special Price to change grouped.phtml table

Question

I am trying to edit our grouped.phtml table so that when a product has a special price it displays different columns.
I have edited my grouped.phtml page to include these columns but can not work out the correct PHP statements to make them show only when a product has a 'special price'.

I have tried: <?php if($_product->getSpecialPrice() ): ?> and also <?php if($_product->getSpecialPrice()){ ?> but this does not seem to work.

I have also found another post showing how to display an icon for products with special price: https://stackoverflow.com/questions/17590849/dsplay-sale-icon-on-special-price-products-in-magento-only-at-homepage-it-is-sh

But again this doesn't not work for me.