This is the normal UK PC Keyboard Layout:
We can see the backslash is on the left-bottom corner (right of shift).
But the mac configuration for UK PC layout, the backslash is on the left-top corner (left of the number 1), see the setting as follow:
So when I use both mac and windows together, this key always confuse me with different output!
UK layout keyboard is ISO standard and the Mac also detects ISO. The only issue is the key on the left of z is switched with the key on the left of 1.
The layout of the UK keyboard:
- the key on the left of z should be:
\and| - the key on the left of 1 should be:
`and¬
But mac switches them.
Best Answer
It appears to be controlled by what you actually have connected... but there is something else going on I'm still trying to hone down.
The best conclusion I can come to at the moment is "it's a bug" but one that seems to be at least partially fixed in High Sierra & Mojave.
This is a UK Apple Keyboard on Mojave [confirmed identical on High Sierrs]
When you first open the panel, it shows as ANSI.
Press Shift [which I discovered by accident trying to take screenshots] & it changes to ISO.
Then add British PC & it seems to retain that information...
Now I've persuaded it to show like that I can't 'break' it again, it seems to stick so far.
However, testing on El Capitan, I can't persuade it to flip to ISO, no matter what I do - it stays as ANSI...
Test on the El Cap machine, swapping a TextEdit document from British to British PC - even though the control panel still claims it's ANSI & after clearing all keyboard prefs & re-detecting the keyboard...
The Mac 'knows' it's ISO, but won't display as that in the Keyboard Input Sources control panel.