This is Gallifrey: Our Childhood, Our Home

 was. . . ''a piece written by Murray Gold. It was used in the series 3 episode Last of the Time Lords. The theme played near the end of the episode, starting with Master's death and through as The Doctor mourned him and watched his pyre burn.

Episodes used in
''Series 3 (Doctor Who)
 * Utopia (TV story)
 * The Sound of Drums
 * The Last of the Time Lords
 * The Doctor's Daughter
 * The End of Time (TV story)''