"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.