Green & Black's was officially purchased by Cadbury Schweppes in May 2005, but I have noticed in recent years that the fair trade mark has been dropped from all their bars, except Maya Gold (which has had its cocoa content reduced from to 50). I have had trouble tracking down the truth of the 'relationship' between Caburys and Green & Blacks, but I think the fair trade mark disappeared about the time that Cadburys bought a 5% stake in Green & Blacks.
Since this happened, the range and marketing of Green & Blacks has expanded hugely, including carpet-bombing of the various new flavours onto supermarket shelves. Sadly, this has driven many smaller, fair trade, brands off those shelves. I even had to take a box of Green & Black's off the shelf just so I could reach a fair trade bar that was hidden behind it on a recent trip to my local shop.
Here is the web address to a long article about the people who actually grow the cocoa beans used in Green & Blacks Maya Gold chocolate.
I think because Green & Black's was established as an ethical company selling organic, fairly-traded chocolate, most consumers assume that it is fair trade. It ain't! It's Cadbury's!