Sixth Doctor Colin Baker made a joke in his column for This Is Local London about how young new Doctor Matt Smith is, saying:
“As if David Tennant hadn’t already proved the visibly beneficial power of time travel on the genes, the imminent new one, Matt Smith, we are told, is so young that he is likely to be asked for ID if he tries to purchase an intergalactic gargle blaster in licensed premises either side of the Atlantic.”