So one of the wings is a really early one with the four corner hole horn grill fitting, this being the rh grill. The grills have been replaced at some point and two extra tabs added on to accommodate the later two mount grills. U clips are used to strengthen and improve the screw pull on the tabs. One on each hole . The screws are not shown but weren’t great. I know new kits are readily available.
It would be cool to source 4 hole grills, even repro ones and step the lh wing back to 4 hole mount. I just checked and Roger Bray does the 4 hold for circa £130 a pop, whereas the 2 holes are about £42 a pop…………. I will have to think on that, its a lot of cash.