Really appreciate your assistance Aadami.
I have tried the "view Injection" approach you mention in your post and I have created my ClientView with populated ViewModel with the following code:
var clientView = _unityContainer.Resolve<IClientView>(new ParameterOverride("client", client).OnType<ClientViewViewModel>());
_regionManager.Regions["MainRegion"].Add(clientView);
I can see the view added to the MainRegion if I inspect the _regionManager.Regions["MainRegion"].Views collection but the view is not shown, have I missed a step?
Thanks again for help