I had to get to the uninstall update functionality via the inistial Windows startup screen/power/advanced route, which gave me back version 1603, and my double monitor functionality. I tried to roll back to 1603, using the control panel etc, but the rollback failed and just sat there for 36 hours.
mI contacted the manufactruere of the laptop (Proline) who advised they no longer support the machine. I contacted Intel, who could only refer me to the latest drivers for IntelHD4000, which still didn’t work. After the update to 1709, Windows 10 no longer allowed the Intel HD4000 drivers, and overwrote them with the generic Windows one, with the result that Windows does not recogneise the other monitors at all. My laptop’s graphics are onboard Intel HD4000, with which I have two external LG monitors, using either Windows10 or Displayfusion to configure the settings.