Teeny tiny train

I’m not a rail enthusiast like Mr. Beewatcher, so I daresay there’s a particular name for this little thing. Anyway it was beetling happily on a mission on the mainline today.
Amazing the things you see just on the way to Tesco.
I often stop on this bridge because there’s a big buddleia bush at the end of the wall, and its purple flowers are covered in bees in the summer.
No flowers or bees today. Summer really is over :(