Fame at last! There's this song by MJ Hibbitt and the Validators
I moved down South
To London and discovered the joys of the Overground
It's a whole other set of tracks
Not shown in back of diary maps
It's full of Mystery Trains
Let's take the Mystery Trains
New Cross, New Malden, Gospel Oak
Barking, Bickley, Blackhorse Road
Thames Ditton, Forest Hill and Penge
They'll take you where you're going and if you're lucky back again
Upon the mystery train
There's always mystery trains
Long live the mystery train