I think whats happened is that people were speculating loads a while ago.... so theyve brought him in for it. BUT... i am sure the Stig isnt always one person. Maybe he has done it a few times and is retiriong? because when you show yourself as the Stig, your contract ends. So maybe.
He's been the main "Stig" for a while, they've had a couple since they killed off the one in the black suit. They do have others tho, usually for foreign stuff, like the time they did a skido race, that stig was a pro skido racer, also the fat american stig was a fat guy, i reckon?!?!
He appears at the end of one of the new Top Gears, at the end of it all Clarkson goes "You know what? I don’t think that Michael Schumacher is The Stig..."
So...
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The guilty shall paay, he'll stop them dead, the last they will seeee, is a white, deaths, heeaaad!
if you google image that collins dude there is a picture of him somewhere dressed as the stig without his helmet on....its been him now for a while me thinks