Teddy Bears' Picnic

"Teddy Bears' Picnic" was a song that Isobel Watkins put on her gramophone while she and Zoe Heriot relaxed. (TV: The Invasion)

The Second Doctor, having lost his recorder, started whistling the tune instead, much to the distress of Jamie and Zoe. (PROSE: Briefly Noted)

Behind the scenes
The tune, one of the most recognisable children's tunes of the 20th century, was not specifically named in The Invasion, but it was in Briefly Noted.