The instructions in the link posted above by Marat worked for me.
I first uninstalled update KB3035583 though as it seemed to be stuck so that the last check whether my PC is suitable for Windows 10 was last month and I could see no way of re-checking. I then re-installed KB3035583 before following these instructions in the link:
Instructions to run the tool:
1. Go to https://www.dropbox.com/s/0u0au9xgy6ss18p/win10fix_full.zip?dl=0
and download the file.
2. Copy the win10fix_full.bat file to anywhere else like desktop.
3. Right click the file and click run as administrator.
4. Follow the screen instruction untill to come to main menu screen.
5. On main menu screen do step 1 first and check if you go the updates insalled and and then press any key it will take you back to main menu.
6. Now do step 2 which only takes like 1 second and should have the icon in the task bar.
The little Windows 10 icon appeared in the task bar and right clicking it gave me the option of reserving Windows 10. Clicking this opened a box requesting my email address and after submitting this I now appear to have successfully reserved my copy. This time I encountered no problems suggesting incompatibility with the Parallels graphics driver.
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