Me again, sorry!
I downloaded the 3.1 image and am using it on a Pi B. I have the GPIO adaptor (v1.2) but have been unable to get it working from the RetroPie setup script. I have gone in and made sure it was using V1.x (option 5) and polling buttons and pad (option 2). But it doesn’t seem to load, no joystick devices in DEV and emulation station doesn’t see any controllers attached. Have I missed something?