I think the stig is never one person, at the moment its one guy but no doubt he will get fed up or want to move on then there will be a new stig (obviously without the viewers knowledge)
personally I dont give a monkeys but I think the BBC feel they need to keep the mystery over this character to enchant top gear viewers.
yes, the programme is a big seller overseas, and the identity of the Jog... I mean, the Stig... is in effect part of the brand; so they're right to try to protect it. I imagine some of the arguments to the contrary are being put forward by Murdoch publications, which are united in opposition to the existence of a rival like the BBC. Also, it's a Murdoch company that is publishing the book in question. So no possible bias there.
I know a bloke whose friend's wife met someone who once went to a bash at the BBC and was told that Jagger-Joyne shags the Stig and sometimes drives on Top Gear when he is cream crackered.
It's part of the show and one (of many) reasons why it's a good show. Better than most shows that are on at the minute! They should have the right to stop something that is going to ruin a tradition of the show!