Prof. Iain Stewart = Bear Grylls
Listening to him, you can hear Bear Grylls talk with a Scottisch accent. Remember the Billy Connolly = John Cleese post?
As has been the case with Cohen/Reagan, Will Smith/Randy Jackson and Obama/Osama/Cruise, the proof is in the ears. Ears are known to be unique to an individual and in some cases are used for electronic identification.