Umb 7.6.3

Just upgraded a site to 7.6.3 (from 7.4.1) and recoding views and partials to use ModelsBuilder.

I have a partial that puts out a list of news articles picked using an MNTP. However, can't get it to work using the documented method.

    @inherits Umbraco.Web.Mvc.UmbracoViewPage<IPublishedContent>

    @{              
        if (Model.HasValue("articleList"))  {
            var articleList = Model.GetPropertyValue<IEnumerable<IPublishedContent>>("articleList");

            foreach (var article in articleList) {

               Some more code    
            }
        }
     }

I get a YSOD saying Object reference not set to an instance of an object. on the foreach line.

The page that invokes this uses:-

@inherits Umbraco.Web.Mvc.UmbracoViewPage<ContentModels.Home>
@using ContentModels = Umbraco.Web.PublishedContentModels

and

@Html.Partial("HomePageArticleList", Model)

The master page uses:

@inherits Umbraco.Web.Mvc.UmbracoViewPage<IPublishedContent>

I'm a fan of ViewPage rather than TemplatePage ;)

Any advice appreciated.

-Craig