C# - Relative URL Not Working In System.Web.UI.UserControl?

public class foo : System.Web.UI.Control
{
public foo()
{
var a = new HyperLink(){ Text="Test", NavigateUrl="~/abc.aspx"};
this.Controls.Add(a);
}
}

The above code works properly, and when added to a page will successfully identify the tilde / ~ symbol and convert the url into a relative url.

However, when I change the derivation of the class to System.Web.UI.WebControl it does absolutely nothing, and leaves the tilde / ~ intact.

I had a look at System.Web.UI.Control which implements the IUrlResolutionService interface, but still can't seem to get System.Web.UI.WebControl to resolve urls.