Capaldi was born in April 1958. When he makes his debut in the Christmas special, he will be 55 years 8 months old. How does that compare?
|Actor||Born||First appearance||Age at first appearance|
|William Hartnell||January 1908||November 1963||55 years 10 months|
|Patrick Troughton||March 1920||October 1966||46 years 7 months|
|Jon Pertwee||July 1919||January 1970||50 years 6 months|
|Tom Baker||January 1934||June 1974||40 years 5 months|
|Peter Davison||April 1951||March 1981||29 years 11 months|
|Colin Baker||June 1943||March 1984||40 years 9 months|
|Sylvester McCoy||August 1943||September 1987||44 years 1 month|
|Paul McGann||November 1959||May 1996||36 years 6 months|
|Christopher Eccleston||February 1964||March 2005||41 years 1 month|
|David Tennant||April 1971||June 2005||34 years 3 months|
|Matt Smith||October 1982||January 2010||27 years 3 months|
So, both Troughton and Davison have handed over to actors born before them. In addition Colin Baker and McGann have handed over to actors who take on the role at an older age.
Hence, out of the 10 regenerations we have had, 4 have seen the Doctor get older, and 6 younger.
There is also the anomalous position of John Hurt, who in the Season 33 finale, The Name of the Doctor in June 2013, was revealed to be the Doctor. Hurt was born in January 1940, making him 73 years 5 months when first appearing. If we take him to be a missing Doctor between McGann and Eccleston, then we are looking at him being between 56 years 4 months and 65 years 2 months when "debuting". Whether Hurt is the Doctor is something we will have to wait and see.
Interestingly, Capaldi was born before all the actors who have played the Doctor from McGann onwards, and he is the first actor to play the Doctor since McGann to have been born before the opening adventure, An Unearthly Child, was shown. Eccleston was born between the final episode of The Edge of Destruction and the first episode of Marco Polo; Tennant was born between the second and third episodes of Colony In Space; and Smith was born between the final episode of Time Flight and the first episode of Arc of Infinity
At 55, Capaldi is the second oldest actor to play the Doctor. I don't think this matters. Ultimately, the question is whether he does a good job of it.
Interesting that Hartnell's portrayal is that of an old man, but Capaldi doesn't strike me as old. Middle-aged perhaps, but not old. And if he manages 4 years, he could be the oldest actor to leave the role.
With this, I want to have a look at a spin-off, The Sarah Jane Adventures, which began in January 2007, with Elisabeth Sladen reprising the role of former companion Sarah Jane Smith. Sladen was born in February 1946, so was 60 years 10 months when this began. Did anyone complain that she was too old for the role? Not as far as I'm aware. Doctor Who can work with an older lead.
And when we look at the companions, Catherine Tate was born in May 1968, so was 38 years 7 months when she first appeared as Donna Noble in The Runaway Bride and 39 years 11 months when Donna became a regular companion in Partners In Crime. John Barrowman was born in March 1967, so was 38 years 2 months when he first appeared as Jack Harkness in The Empty Child/The Doctor Dances in May 2005, and 40 years 3 months when his name first appeared in the opening credits in Utopia. Tennant is in the unusual position of having had two companions played by people older than him.
Also born before Tennant is Alex Kingston, born in March 1963 - I guess that the Doctor finally being played by someone older than her could cause changes to the dynamics of the Doctor/River Song relationship.
No, Capaldi is not too old. He will be fantastic, absolutely fantastic. Yes, it'll be a change to the show, and not a moment too soon.