OK Serial communications sorted. I messed around with zadig but couldn’t get it to load a virtual COM port for me. However when I followed @BDub’s instructions for installing the sparkcore.inf driver it worked perfectly happily alongside the zadig installed USB driver.
The process was:
press mode and click reset get yellow flashing LED
run zadig and install USB driver for Spark Core
run BDub’s Serial software so that the spark is waiting for serial input (I dare say listening mode would work too but I’m quitting while I’m ahead) and follow his instructions - briefly
go to control panel/system/device manager and find Spark Core
right click, install driver (delete existing driver first in my case after messing with zadig)
The zadig driver is there when the yellow LED is flashing
The sparkcode.inf driver is there when the cyan LED is breathing
It is a mystery to me but it works so many thanks to Bdub and @seulater
Now if some wise soul can get the Serial communications going through the Netbeans Terminal window that would be awesome.