And the answer is . . .

My first discovery 66 years ago was the keyhole behind the little doors.That part was easy. Finding the key was the hard part.

As Moonfairy, EllyJay and 59 suggested yesterday the answer lies in sliding panels.

First, the left hand side of the base slides back. Then the front panel slides to the left. That reveals a little drawer. It makes a tinkling sound to alert you that you are about to be burgled. Inside the drawer is the key which opens the roof up to reveal your saved fortune.

Three generations of children in my family have had fun working this out.