He was also in an earlier episode of Dr Who with DT if I remember....
Context free pronoun. Who exactly?
I assume that you mean Peter Capaldi. If so, you are correct. The episode was The Fires of Pompeii. Capaldi played the character Lucius Caecilius Lucundus, who, according to Wikipedia, was a real person who's home partially survived the eruption in 79AD.
Hardly the first time that a writer has decided to co-opt a real historical character into a story. One random example, remember Harry Potter and the philosopher's stone? Nicolas Flamel was a real person who, according to some stories (and I stress the word stories) actually discovered the philosopher's stone, a 'fact' witnessed by the 'fact' that there is no record of his death.
Back to Dr Who.
Of the recent Doctors, I liked David Tennant the best. Davis' writing was seriously negative with a strong anti-religious tone, but the stories were good. I also liked both Billie Piper and Rose Tyler. Piper is really attractive and a really good actor. I really liked Rose Tyler too. She was believable and not wide eyed and fawning. Well, believable insofar as someone travelling through time in a tardis, with a time lord, facing Daleks, Cybermen e.t.c. and not totally freaking out can be considered believable!
Freema Agyeman is an ok actor but I couldn't really believe Martha Jones. Perhaps a reflection of the so-so acting?
Catherine Tate is really good at playing characters. Her whole career is based upon it. It shows. Donna Nobel was so bloody loud! She talked, she interrupted, she wanted explanations, she sometimes looked scared. I can relate to that. Her responses were the kind of responses I could imagine myself having. She was also a big change from the pretty girl companions. Yes, I know that a cute face, curves and bumps brings in the boys (I had a crush on Sarah Jane Smith since I was a boy), but what I want most out of my entertainment,is, well, entertainment. Bringing in someone mainly because they are good looking doesn't work if they can't act. Catherine Tate can act.
Karen Gillian is also a very good actor. Not really what I go for (wrong size, shape and hair. Think Lis Sladen, Carrie Fisher, Clara Bow, Louise Brooks). Amy Pond took a while to grow on me, but after an uncertain start, the wonderful sarcasm and occasional bad temper won me over. So normal.
Then we move on to Matt Smith. Perhaps it's the writing, perhaps it's the actor, but I never really liked Smith as the Doctor. Not hatred, derision, or even active dislike. Just, what, damning with faint praise? He was OK. An also ran.
Then there's Clara...
Jenna Coleman? Gorgeous! Short, cute, curvy, add her to the above list after Louise Brooks. Clara Oswald? Hmmm.
Again, maybe it's the writing, but I don't get the character. "She ran the whole gamut of emotions from A to B" (Dorothy Parker). She's flat (the character, not Coleman!!). No great fear, no great anger, no great sarcasm. Perhaps there will be a bit more range in the new series (I saw a tear, possibly water, possibly aided by an onion, but nevertheless a tear in Deep Breath).
Peter Capaldi. What can I say? Only time will tell.
I would just like to say at this point that I am not a sad Dr Who fan. Really. No, really! I just like the program. The fact that I have been watching Dr Who since at least 1973 is simply a reflection of the quality of the program making, not an indication that I am a sad, nerdy Dr Who fan. OK? Good! Well, that's nice and clear then. Just a fan of good entertainment...