I have view model which has another child model to render the partial view (below).
public class ExamResultsFormViewModel { public PreliminaryInformationView
You can add the HtmlFieldPrefix to the top of your partial view:
@{ ViewData.TemplateInfo.HtmlFieldPrefix = "Contact"; }
This is the same approach as that described by @cpoDesign but it means you can keep the prefix in your partial view if you need to do that.