The book I’m looking for is as follows:
Children’s book – from the UK
I read it in the UK when i was a kid in the 1970s
It was illustrated but with line drawings – was for older kids, maybe 7/8 and up?
There was a story in it about a family who takes an elevator down into the ground, and they whistle to each other if they get lost.
It was a collection of stories for kids.
It might have also had poetry in it
This story has haunted me for years, no idea if it will ring a bell with someone somewhere