To discover if you are affected by a Provisional Adoption Order issued in the UK is quite easy. It is a two step process and requires that you have access to your UK Birth Certificate.
1) Your first step is to look at the long version of your birth certificate issued by the General Register Office. There are two versions of your birth certificate, a long version (complete information) and a short version (contains your name, gender and place of birth). It is only the long one that will give you the necessary information. On a birth certificate for someone adopted, column (6) contains the the date of the adoption order and description of the court by which it was made. My column (6) contains the words:
Provisional Adoption Order, Second October 1969, Sheffield County Court
If you find similar wording it means that you too are provisionally adopted.
2) Your next step after confirming that you are provisionally adopted is to look for further information of an adoption. This would take the shape of an adoption form issued in the country that your adopting parents come from. You should also have other identifying papers or a social security number issued by the same country as the adoption happened in. So for example I would have been issued with a social security number from the USA if I had been legally adopted there. If you cannot find any of these papers then you will need to ask your adopting parents for them, this can of course be tricky. At this point if you have found these papers or your parents have given them to you, everything is fine and you will have been legally adopted.
If on the other hand you have not been able to locate these papers yourself and your adopting parents do not have them then you will need ask them for the details of your legal adoption. Once you have the details you will need to approach the authorities and ask them to do a search for your adoption papers. In my search I have found the authorities to be sympathetic and helpful in this. If at this point your papers are discovered, read through them to verify that everything is correct and rest assured that you were legally adopted.
If you, like I did, discover at this point that there never was an adoption in any country, you have entered into a profoundly strange and difficult place. The first thing you must do is seek legal help to sort this mess out. I wish that I could give clear guidelines but currently there are none. The second thing you are going to need is an adoption counsellor to help you realign your life as there are some major adjustments ahead. I wish I could say that everything will be sorted and go back to normal, but unfortunately the fact that you were not legally adopted ensures that it cannot return to normal even if and when everything else is sorted.
Provisional Adoption Order (UK 1958) 
Hello,
I have a provisional adoption order. I found out my parents never legally adopted me. I do have a social security number. Does this mean anything? I was deported back to London is there a clause that protects me from being deported since I have this order?
Hi Ebony,
Sadly a US social security number does not help in this matter and it will not stop your deportation. I do not know the criteria for gaining a US social security number but one thing for sure is that it was easier to get one in the past than it is now. The UK Government does not see this as being their problem, their defence is that they originally did the ‘right thing’ in processing your provisional adoption order and it is no longer their responsibility.
My advice is to seek legal council to see if you can claim US citizenship through other means. This can be a much more complicated if not impossible process as requirements have in recent years been increased. I wish you the best of luck in this and am sorry that I cannot offer you better advice or hope.