To close this off, the serial cable arrived today, and Configuration Manager immediately recognised the connection on COM4 all is well.
I can see some scope here for clear documentation, with all of the changes in Configuration Manager and ASCOM and so on.
Roger, Atherstone, England, UK
Mount: ES iEXOS-100, Celestron NexStar SLT
OTA: Celestron 127/1500 Mak , Svbony 60mm Guide scope
Camera: Svbony Sv305, Sv205