Should have looked closer at the logs:
A duplicate name has been detected on the TCP network. The IP address of the computer that sent the message is in the data. Use nbtstat -n in a command window to see which name is in the Conflict state.
nbtstat does show the hosts name listed twice in <00> and <20> on all adapters (Local, VMnet8, VMnet1) However none of the VMs have the same computer name. What causes workstation to assume the hosts computer name and throw the duplicate message? As I say as soon as I turn off the VMs the network is restored on the host.
Puzzling.