Since writing the above I have tried this joystick on my laptop also running Vista and it behaves impeccably.
If I look in device manager on my PC (which is where the problem lies) under Human Interface Devices, I have "HID-compliant game controller" whose properties inform me that "no driver files are required or have been loaded for this device." In spite of listing a Microsoft driver in the appropriate panel in properties.
In "Sound, video and game controllers" there is no mention of a game controller.
Enlightenment still sought please!