The model, 21, and her little sister Erin were making their way to Swansea in First Class (OBVS!) and it wasn't long before they needed some entertainment.
What to do? Stretch out on the tables, hide in the luggage hold, and plank on the back of the seats of course!
It's a good job the carriage looked empty!
The super fun sisters took snaps of one another as they went.
Fellow model Erin, 17, commented: "this weirdo shouldn't be allowed on trains #toinfinityandbeyond @missamywillerton."
Yep, totally norm behaviour ladies!
How nice is it to see the sisters having fun together during their journey on Saturday (14 June)?
Amy and Erin have done a bit of modelling together recently too, and it's clear that pretty genes (and slightly loopy genes!) run in the family.
What's the most fun you've had with your sister? Tell us below, as the best comment from across the website each week wins £50!
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