MapPolygon polygon = new MapPolygon()
{
    Points = coll,
    Fill = new SolidColorBrush(fill),
    Stroke = new SolidColorBrush(stroke),
    StrokeThickness = 2,
    Tag = p
};
 
System.Xml.Linq.XElement xTextBlock = new System.Xml.Linq.XElement("TextBlock");
xTextBlock.SetAttributeValue("Text", "Name: " + p.Name + "\n" + p.Type + " Name: " + p.OwnerName);
 
DataTemplate template = (DataTemplate)XamlReader.Load(
    @"<DataTemplate
xmlns=""http://schemas.microsoft.com/client/2007"">
" + xTextBlock.ToString(System.Xml.Linq.SaveOptions.DisableFormatting)
       + "</DataTemplate>"
    );
 
polygon.CaptionLocation = new Location(p.PointData[0].PointLatitude, p.PointData[0].PointLongitude);
polygon.CaptionTemplate = template;
 
shapeLayer.Items.Add(polygon);

The new way I'm doing it is like this

<UserControl x:Class="WIMMS.UI.Module.Main.Controls.SimplePolygonInfo"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:local="clr-namespace:WIMMS.UI.Module.Main"
    xmlns:telerik="http://schemas.telerik.com/2008/xaml/presentation"            
    mc:Ignorable="d"
    d:DesignHeight="300" d:DesignWidth="400">
 
    <Grid x:Name="LayoutRoot">
        <telerik:MapPolygon x:Name="MapPolygonItem" Points="{Binding PointData}" Fill="Red" Stroke="Red" StrokeThickness="2"/>
    </Grid>
</UserControl>
public partial class SimplePolygonInfo : UserControl
    {
        private IEventAggregator _events;
        private ICommonService _commonService;

        public SimplePolygonInfo(IEventAggregator events, ICommonService commonService)
        {
            InitializeComponent();
            _events = events;
            DataContext = this;
            _commonService = commonService;
        }

        public static readonly DependencyProperty pointsProperty =
DependencyProperty.Register("PointData", typeof(LocationCollection), typeof(SimplePolygonInfo), new PropertyMetadata(new LocationCollection()));
 
        public LocationCollection PointData
        {
            get
            {
                return (LocationCollection)GetValue(pointsProperty);
            }
            set
            {
                SetValue(pointsProperty, value);
            }
        }
    }
And the logic changes to this:

SimplePolygonInfo polyInfo = _container.Resolve<SimplePolygonInfo>();
polyInfo.PointData = coll;
shapeLayer.Items.Add(polyInfo);
Is it even possible to do it this way?
If I do something such as add a text block above the map polygon I can see that.

<Grid x:Name="LayoutRoot">
    <TextBlock Text="Test Text"/>
    <telerik:MapPolygon x:Name="MapPolygonItem" Points="{Binding PointData}" Fill="Red" Stroke="Red" StrokeThickness="2"/>
</Grid>
But can't see the polygon still.

Thanks for the help