All ok - worked it out.
I ended up levering up the side of the plug (which looked like a washer around the screw), then pushing it back to leave a little gap around the plastic screw. Screw driver in the gap popped the screw out easily.
Now I've just got work out what's wrong with the windows. GOing to replace every fuse in the manul that mentions windows.
Thanks for the reassurance to give it a tug.
MattGo to the full post