The Taxi Driver is the person escorting Adam to the Mansion in Helston. He can be briefly seen in the introduction video of the game, Shadows, though his face is barely recognizable because of the shadows.
Mark Bedford: We actually did some live action filming at the Coventry Museum of British Road Transport. The taxi-cab scene at the start of the game was filmed in a real cab. It was the oldest taxi in England... and what's more I was the driver.