Web Service as function return value [RESOLVED]

[GlenW]

I want to be able to switch between a local test Web Service and a server
based live Web Service.
When testing numerous web forms I need to switch their Web Service reference between a local development service and the live one.
At the moment this involves replacing the declaration 'TestWebService' with 'LiveWebService' in each form.
What I would like to do is have a utilities class that has a static function
that returns a reference to the appropriate web service depending upon a key
in web.config.
I would be able to do this if I knew how to declare the return value of the
function:

internal static ???????? GetWebService()
{
   string lstrWebService = 
       ConfigurationSettings.AppSetting["WebService"].ToString();
   if(lstrWebService == "Test")
   {
       return ????????;
   }
   else
   {
       return ????????;
   }
}

Anyone know what the ?????????s should be or if what I want is not possible.