Hi Linda29
Welcome to Rootschat
As it appears he was adopted shortly after birth, he most probably had his name changed by his adopted parents to one that they would have chosen had they given birth to him.
He may also not know that he was adopted.
Unless you know the name he was adopted into, there is no way of linking an entry in the GRO birth index with an entry in the GRO adopted childrens index (an adoption certificate will confirm his date of birth and the names of his adopted parents but not his birth mother), and virtually no chance of finding him through the normal channels.
At this stage, if you haven't done so already, the best way forward is to register your name on the GRO adoption contact register here
https://www.gov.uk/adoption-records/the-adoption-contact-registeror here
http://www.adoptionsearchreunion.org.uk/default.htmor here
http://www.missing-you.net/categories/adoptions.phpin the hope that he too has registered to find his birth family.
I had a look at the birth index and note that there are other children with this surname/mothers maiden name combination but he was born away from the area the family were living in Berkshire. It is possible that he was adopted away from the Croydon area which is why Croydon adoption archive couldn't help further.
The entry in the birth index would have been amended by order of the Registrar General on completion of the adoption.
Also be mindful that we have a 'no living people' policy here so information can only be of a general nature. Anything specific should be sent to you by the personal message system but you need a higher post count to be able to use it.
http://www.rootschat.com/help/pms.phpGood luck
Dawn