I note that the Description on the YouTube page with the recording states,

The piece was inspired by an old steam locomotive called 'Puffing Billy', seen by the composer while on holiday on the Isle of Wight.
https://www.youtube.com/watch?v=6Wy73UYbNrs

Not the "last" anywhere. However, I've no idea how accurate this is either, of course.

Although I'm certainly of an age where I watched Captain Kangaroo every morning, I don't recall this song from it. *shrug* But I don't recall any OTHER theme song from the Captain either.

BB,
NightWing