Which series of children's classic books often included the characters "Aunt Fanny & Uncle Quentin"?

in everyone of those books there is a secret passage leading somewhere

Grew up on Enid Blyton, The Secret Seven was good too, a few of her books have been banned due to politically incorrectness.

I only remembered Timmy the dog.

Never heard of it. This is why I love the Majority Opinion clue. Thanks!