Complex sentence: The Doctor refers to humanity's first venture outside the solar system as taking place in the time of Captain Adelaide Brooke's granddaughter, despite his previous statements in classic series episode "The Invisible Enemy" that this milestone occurred in the 51st century.
Split into simpler sentences: The Doctor refers to humanity's first venture outside the solar system as taking place in the time of Captain Adelaide Brooke's granddaughter. In the classic series episode "The Invisible Enemy", the Fouth Doctor states that this milestone occurred in the 51st century.