But how *do* they do it?!

I observed *the* cutest conversation at Embankment today...

Small child: Mummy, is the Circle Line called the Circle Line because its a big circle??
Mother: Yes. Well done! That was really good remembering

*she goes back to looking through her handbag having finished the conversation*

*pause*

Small child: Mummy?
Mother: Yes?
Small child: You know how at home the train comes out over the ground and you can see it and Daddy told me that's how they get the trains in to the tunnels??
Mother: Yes... *clearly wondering where this is going*
Small child: So how do they get the trains into the Circle Line?

Does it say something about me that I often wonder the same thing??
x