Captain Jack has an American accent. They are British because the TARDIS translates the language into what the companion/viewers understand. When translating to English, the default accent is British, for some reason.
Why the Doctor didn't come back for Amy for 12 years - the whole course of history would change if he had been on time! HIS personal destiny would have changed if he had been on time! If Mels were to succeed in killing him at her younger age, then Rory an