"If you're having trouble letting go of the Eleventh Doctor, the appearance of teacher Adrian - aka actor Edward Harrison - probably didn't help..."
Big hair? Check. Kind face? Check. Bow-tie? Check. Handsome-looking and well-fit for a time lord? Check and check.
Yet despite all the evidence of Adrian being the 11th Doctor... I believe that you can be certain of the contrary. Even the 12th Doctor was appealed to the young man that looked quite like his old self. However, this man has no right to take place of the 11th Doctor - and hopefully Moffat keeps it that way!