Rather interested in the below:
"Despite giving away Hyper-V, Microsoft never won more than about 20 per cent of the market."
Maybe by number of hosts installed or VM's running possibly, but in terms of customers I'd put money on it Microsoft has more Hyper-V customers than VMWare has ESXi customers.
Source is purely my own experience: I worked at a medium sized crisp factory (600 employees) about a decade ago where I ran vSphere, and I then moved to a pharmaceutical firm with > 20,000 users who also used vSphere for a couple of years. I then left and joined a small/medium MSP with about 90 customers. 2 were using ESXi, about 60 were using Hyper-V and one was using Xen. (Rest were so small it was physical servers only or no servers at all!).
Since then I've joined a consultancy and one customer (50,000 employees) was running vSphere and is looking to replace with Hyper-V, and another customer (800 employees) is already on Hyper-V.