British Mac Keyboard - § and ` key the wrong way around I'm running High Sierra 10.13 on a Macbook Pro Touchbar 2017 with British keyboard.

When at the desk I use a Corsair K70 mechanical keyboard set as British Mac layout. I don't look at the keys to type and prefer mac layout so no problem.

Seemingly randomly though, my `/~ key which is usually left of z started producing §/±, which is usually left of 1, and vice versa. I've checked Keyboard preferences and its set as British Mac keyboard, but the layout image is wrong, this is what I get:



Whilst this is what my friend gets, and what I would expect (this one also matches a UK Mac keyboard layout whilst mine does not):



The keyboard on the Macbook itself works fine with the correct keys.

I think this may have gone wrong when I installed the latest macos update.

The options panel offers very little flexibility, I've tried swapping to a US keyboard and deleting the British layout then adding it again but no luck. Anyone know how to correct this?
Your machine thinks your keyboard is of the ANSI type when it is actually of the ISO type.  See this note for some possible help.