Charlie Baker was the grandson of Gertie, who, at a young age, was very interested in her stories about the Doctor. As he grew up, though, he came to believe the stories were false.
On 26 September 2016, the Twelfth Doctor arrived with Clara Oswald on a Time dragon and took Gertie and Charlie home. When the Doctor got his TARDIS back, the Doctor took them on a journey to Mars. (COMIC: Super Gran)