Hi, have you considered contacting Social Services and asking for their help? They can refer you to an Intermediary Service who can obtain his adoption file and get the ball rolling in trying to find him for you. It's a long process, well can be depending on what the I.Serv is like. Or look for an Intermediary in the area of the adoption. Good luck. Feel free to send me a PM (Private message) if you need more help/advice:)
Shirley