The only reason I'm posting this is because I was stuck for a few hours and the internet had tons of conflicting fixes for this that led me nowhere. Still stuck with GPT errors and a whole lot of general bollocks. For some reason this refused to work on the USB port on the left of my macbook and for reasons known only to Job's & Gates' lovechild, worked on the one located on the right. Sorcery.

1. Bootcamp Drivers Windows 10
2. Install Windows 10 El Capitan Boot Camp

Anyconnect secure mobility client v4 x. On supported Macs running OS X El Capitan, Boot Camp comes with a modified interface that places the ISO image selector and partitioning on a single screen, allowing a user to easily select an ISO.

1. Boot Camp supports Windows 10 in Yosemite or later with the listed Macs towards the end of this page. That doesn't mean Win 10 won't work at all if your Mac isn't in the list. I upgraded Win 7 to Win 10 on my 2010 Mac Pro and it runs fine on the Win 7 Mac drivers. Yes, it's supported.
2. Mention, that for MacOS versions prior to OS X El Capitan 10.11 you will need to create bootable Windows USB. Download Windows ISO file; Open Boot Camp Assistant (Go to Applications Utilities) Define the Windows partition size choose downloaded Windows ISO file; Format Windows partition and go through all Windows installation steps.
3. El Capitan’s Boot Camp has USB drive-less Windows setup, but not all Macs are supported. Boot Camp, the Mac’s built-in software for dual-booting between OS X and Windows has been given some love in the new El Capitan software update and now features a slicker Windows setup that no longer requires a USB thumb drive, as discovered by Twocanoes.
4. One such finding relates to how El Capitan handles the installation of Windows through the Boot Camp Assistant. If you’re familiar with Apple’s Boot Camp Assistant, then the first thing you’ll notice on El Capitan is that the main interface has changed. The internal changes now mean that the ISO image option, and the ability to partition.

This is what worked for me, I can't guarantee that it will work for you and I'm by no means a Mac expert - so use at your own risk. Caveat emptor. No screenshots because of reasons.
What you need:
1. MacBook or other Mac Computer that is listed here: https://support.apple.com/en-us/HT204990
2. Windows 10 64-bit ISO.
3. A fresh USB stick, 8G or more would be fine.
4. At least 100GB free on your Mac for a 64GB Windows install.
What's next?
0. Update your mac if needed.
1. Run bootcamp and select the two options

- Create a Windows 7 or later setup disk

- Download the latest windows support software from Apple

1.1. Click Continue, grab a beer. or three. This takes a while.
2. Exit bootcamp. Because of reasons.
3. Fire up bootcamp and this time select the option to install (only).
4. Drag a partition size that suits you, I went with 64GB - then click Continue
5. Magic happens then the computer would probably reboot right into OSX. Manually reboot and this time hit the Option Key, Feel free to bang away at it. (Disclaimer: Do not bang away at it.)
6. When presented with boot options, please ignore the Windows option. Select UEFI boot.
7. Oh looky, run through the windows install until you get to the Disk screen. At this point choose your desired windows partition created in step 4 and then click format. The next button magically appears and you should now be able to proceed with installation.
8. Magic happens again, then a couple reboots later and Win 10 is done. Grab another beer. or three.
9. The next time you bring up the dual boot screen, Only OSX and Windows would be presented and the UEFI option is gone.
10. Happy dualbooting. Hell you'd be happy too after six beers.

The only reason I'm posting this is because I was stuck for a few hours and the internet had tons of conflicting fixes for this that led me nowhere. Still stuck with GPT errors and a whole lot of general bollocks. For some reason this refused to work on the USB port on the left of my macbook and for reasons known only to Job's & Gates' lovechild, worked on the one located on the right. Sorcery.
This is what worked for me, I can't guarantee that it will work for you and I'm by no means a Mac expert - so use at your own risk. Caveat emptor. No screenshots because of reasons.
What you need:
1. MacBook or other Mac Computer that is listed here: https://support.apple.com/en-us/HT204990
2. Windows 10 64-bit ISO.
3. A fresh USB stick, 8G or more would be fine.
4. At least 100GB free on your Mac for a 64GB Windows install.
What's next?
0. Update your mac if needed.
1. Run bootcamp and select the two options

- Create a Windows 7 or later setup disk

- Download the latest windows support software from Apple

1.1. Click Continue, grab a beer. or three. This takes a while.
2. Exit bootcamp. Because of reasons.
3. Fire up bootcamp and this time select the option to install (only).
4. Drag a partition size that suits you, I went with 64GB - then click Continue
5. Magic happens then the computer would probably reboot right into OSX. Manually reboot and this time hit the Option Key, Feel free to bang away at it. (Disclaimer: Do not bang away at it.)
6. When presented with boot options, please ignore the Windows option. Select UEFI boot.

Bootcamp Drivers Windows 10

7. Oh looky, run through the windows install until you get to the Disk screen. At this point choose your desired windows partition created in step 4 and then click format. The next button magically appears and you should now be able to proceed with installation.
8. Magic happens again, then a couple reboots later and Win 10 is done. Grab another beer. or three.
9. The next time you bring up the dual boot screen, Only OSX and Windows would be presented and the UEFI option is gone.
10. Happy dualbooting. Hell you'd be happy too after six beers.

Install Windows 10 El Capitan Boot Camp