Looking for image of arm flash

Many years ago I was in an FCA unit tasked with radiation monitoring. That task was later transferred to the civil defence.

We had a beautiful arm patch that had a picture of a Heron? Holding a stone in its foot. This symbolised eternal vigilance, because if the bird fell asleep, the stone would drop, thereby wakening the bird.

I'd love an image of this badge. My old badge has long gone as it was changed when that unit no longer had that job.