I Don't Know, But I've Been Told is a traditional military cadence sung by soldiers during training. Brooklyn led the trains in a performance of the song in A Change Is As Good As A Rest.
Brooklyn: We're all rollin' down the line!
Circle: We're all rolling down the line!
Brooklyn: Everybody's doin' fine!
Victoria: Everybody's doing fine!
Brooklyn: Gonna have a real nice day!
Hammersmith and City: Gonna have a real nice day!
Brooklyn: Like we're in the USA!
Bakerloo: Like we're in the... USA. Really!
Brooklyn: Tryin' somethin' new is great!
Ernie: Trying something new is great! Just as long as you're not late!
Brooklyn: Just as long as we're not late! Hahaha!