You really are incredibly strong to be dealing with this atrocity committed by your ex. I can't even imagine the heartache you've experienced by this. Can you see if the police or phone company can put a trace on your phone calls you receive, to see if they're really coming from England? He could say that as a dodge, in case you'd actually come looking. Maybe try one (or all) of the following:
(this may be of help especially: http://www.visaus.com/childabduct.html
National Center for Missing and Exploited Children missingkids.com
Adam Walsh Resource Center http://www.amw.com/about_amw/john_walsh.cfm
National Center for Victims of Crime www.ncvc.org
Or, better yet, call the FBI to ask what can be done about this, if anything. Or if it's true that he's in England, maybe contact the consulate over there.
There has got to be something you can do to track this...ex down and get your child back. At least I pray there is. Don't give up mama!