I have a 2012 13" MacBook Air and it appears that one of the shift keys is stuck down.
I’ve tried cleaning with compressed air, removed the key-cap and checked for damage and found nothing obviously stuck or dirty.
Does anyone have any other ideas I might try as looking at the process to replace the keyboard it looks like a mission and the keyboards themselves appear to be quite expensive.
Any and all advice/recommendations appreciated 
I also have not seen this particular keyboard layout when I’ve looked for a replacement
The MacBook Air keyboard is connected in series with a few other components:
Keyboard (w/ Power Button) —> Trackpad —> IPD Flex Cable —> Logic Board
It is certainly possible for the Trackpad or IPD Flex Cable to be faulty, causing this issue, but if the other keys work then it sounds like a keyboard issue.
That said if you could get access to a spares machine or another Trackpad and IPD Flex Cable for free or cheap, they’re at least worth a shot before stripping the entire machine down. The good old reseating connectors never hurts either.
That layout almost looks like the UK model, but without the pound symbol. Some history of the machine would be useful here, when and where it was purchased, etc. There are a lot of keyboard layouts available and I could be missing an obvious one. On the other hand it could be a standard UK keyboard with some key caps swapped over.
If you do attempt to replace the keyboard yourself, my advice is to get the entire Top Case - that is, the metal chassis of the computer with the keyboard pre-fitted. There are places online that sell just the keyboards for reasonably cheap, but the fitting process is nothing short of hell, involving removing rivets, some tapping and possibly some cutting and drilling if the rivets holding the keyboard in break.
The Top Case w/ Keyboard is more expensive than just a keyboard, but no amount of money saved would ever make me want to take on that job ever again.
Thanks for the information, after doing further testing I think that the machine has some other issues as well as it has now starting going in to a reboot loop - starts to boot fro OS X install media, then gets so far and restarts, have tried 3 different install media with different versions of Mac OS, the screen also seems to randomly loose the back-light to a triangular area taking up almost 1/3 of the bottom right hand sections of the screen and it takes and age to power on or off.
I think this one I’ll just ditch, or hold on to for case part spares.
Sounds like a kernel panic on startup. Not sure about the backlight issue, but could be the panel or driver circuit on the Logic Board.
Coincidentally I have another 2012 coming to me for a keyboard replacement this week, with a dead power button. My own 2012 was a bit of a lemon as well. They weren’t terrible, but definitely not the most reliable Mac I’ve ever come across…
Yeah that’s what I was thinking as I did catch the details of a kernel panic on screen once when it restarted. I’ll assign the machine to the “might be good for parts (throw away soon)” pile.