>Authentication attribute is irrelevant. It's only looking at {Route] attributes.
>
>IAC, if the method is working (as per previous post) then the route map is probable being created OK and there's no need to remove the MapMvcAtttributeRoutes() call ?

Yes, your other suggestion of changing the base controller's calls seems to be working, e.g. I switched from commented now code to what you suggested and all seems to be well:

  //public PartialViewResult SuccessView<T>(T viewModel, string viewName, string message) where T : BaseEditViewModel
        public PartialViewResult SuccessView(BaseEditViewModel viewModel, string viewName, string message) 
        {
            viewModel.SuccessMessage = message;

            return PartialView(viewName, viewModel);
        }