Securing a manual shutter

Hi all

I have the older dome, with the wheels for the shutter, and do not intend to motorise the shutter as it sits outside the house within an easy distance. However, I would like to be able to secure the shutter (from the inside) so that when I am not here, people can't just lift the shutter panel and climb in (the door is locked).

What options have you implemented for this? Photos would be most helpful.

Regards

David O'Driscoll

Brisbane, Australia