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?

Solution 1:

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.