Booting from Windows 8 install drive
Enter repair, then Advanced, then Command Prompt:
diskpart list disk select disk 0 list partition select partition 1 shrink desired=200 minimum=200 create partition efi list partition select partition 2 format fs=fat32
These commands will create the EFI partition. Double-check everything by typing
list vol. You should see a 200 MB partition. You now need to assign it a letter. Do this by typing
assign b:, then
list vol again to see what letter has been assigned.
Now this is done you need to copy the boot files to this newly created partition:
bcdboot C:\Windows /l en-gb /s B: /f ALL
Note: you must replace
C: with the drive letter of the partition that contains Windows, and
B: with the letter assigned to the EFI partition you just created.
I also entered the following commands:
bootrec /fix bootrec /fixmbr