jQuery AJAX appending to Json return data "d:null"

Well it would seem that I just needed to add Context.Response.Flush() before writing to the page.

Context.Response.Clear();
Context.Response.ContentType = "application/json";
Context.Response.AddHeader("content-length", strResponse.Length.ToString());
Context.Response.Flush();
Context.Response.Write(strResponse);
HttpContext.Current.ApplicationInstance.CompleteRequest();

Once I did that everything was fine.