[kall]

I'm thinking of a book I read back in the day..

It was basically about 3 kids who crawled through a hole in a fence and ended up in a magical world.

There were flutterbyes, gum trees that you could eat, a singing river (I seem to recall), a barge with a magic ice cream making machine, some kind of dragon or something that ruled the place, and it was the last of its kind.

There was also a cat...and they avoided it by luring it into a patch of catnip.

Anyone?