Here are some pics of the clips for the middle section of the grille which use the same holes as the GTL.
The are two tabs at each edge of the grille that pass through slots in the bonnet. Fixings for those are large curved spring clips with a slit for the tab. I've misplaced mine momentarily. Many GTL owners just bend the tabs over.
Sorry - I have no spares of either. For the ones in the photo a thick square piece of aluminium with a hole tapped in it and glued to the grille might work as a replacement.