While travelling, the Doctor works to save lives and liberate oppressed peoples by combating foes.
In 1999, Big Finish obtained a non-exclusive licence to produce official Doctor Who audio plays.
Though the programme had been put on indefinite hiatus in 1989, the BBC still published, as well as gave non-exclusive licenses to other companies, Doctor Who stories through various mediums such as novels and comics.
[2] Big Finish Productions, which mostly consisted of fans who started out recording fan audio plays, were given the license to record some of the New Adventures, a series of novels from Virgin Books which had originally been licensed Doctor Who stories, into audio plays.
[3][4] This eventually transitioned into a license to produce original audio dramas featuring the past Doctors, with The Sirens of Time being the first story to be released in July 1999.
[8] Since then, every televised companion has reprised their role in Big Finish (with the exception of Jackie Lane's Dodo Chaplet).
[10] Though the BBC has not echoed the sentiment, executive producer Nicholas Briggs considers the audios to be completely canonical.