It seems to have resolved itself.
Via taskmanager, I closed the multiple tasks it caused to run gobbling up resources and deleted it but after a few hours it came back. This happened a few times.
Eventually I simply renamed VMHost.exe as xyzvmhost.exe and that appeared to stop it.
However on reawakening my PC yesterday, McAfee reported, blocked and removed an unspecified trojan.
The renamed file has now disappeared and my PC is running ok.
Thanks for your potential solutions anyway. I appreciate the effort you all put in.