When the device had moved to the list of Universal Serial Bus Controllers (see my previous post), I again
clicked on Scan for Hardware changes, and this time it went into the Found New Hardware Wizard, and I followed the instructions, as if
I had the driver, and it all seems to have worked.
However, the PicoScope program couldn't find the ADC-200 device, so I decided to re-install the software, and select the USB version of the ADC-200 interface instead of the LPT1. Having done so, it all works.
Thanks a bundle!