Finally, I deleted the ServiceReferences.ClientConfig file from the SL4 app and removed the service reference. Then I added the service reference back again and a new ClientConfig file was created. Adding the reference warned me the first time that there is no policy xml file, but after repeating the steps this warning never appears again. Then I noticed that the address in the ClientConfig file was in an unexpected format:
http://owl.nancy.local/PhotoService/Service1.svc I changed that to be http://localhost/ and it worked. This may have been the original cause of my cross-domain problems, but I didn't notice it in the mess. It turns out that a clientaccesspolicy.xml file is irrelevant and has no effect upon any of my symptoms. It's a complete furphy when debugging on localhost. So there you go, exactly 3 hours to get a hello world WCF service and SL4 app talking. Greg
