Actually I figured it out, I changed the ListModel to
class ListModel {
public string this[string key] { get{return _values[key];} set{_values[key]=value;}}
public int ID{get;set;}
public IDictionary<string,string> _values = new Dictionary<string,string>();
}
And the XAML to
<TextBlock Grid.Column="1" Text="{Binding [Entity1]}" />