Once upon a time there was this massive great elephant we will call Bob. He was stuck in this room. Even he had forgotten how he'd got there.

There were quite a few people in the room. They got in Bob's way and he kept trampelling on them. He roared occasionally and the room shook. He stank to high hell. No one in their right mind could fail to notice that Bob was there.

But they must all have been out of their minds.

"Elephant? What elephant?" they said to each other. "There's no elephant in this room."

Pathetic isn't it? None of them dared deny the potency of the stupid and fairly recently coined metaphor. In the end, I think, Bob - out of pure frustration and boredom - probably trampled everyone in the room to death. But I didn't hang around long enough to give this story a definitive punchline.