Forget crocodiles, sharks, or insects that make you bleed through your arse, Bear Grylls is the scariest thing on TV.

In truth, at first glance ex-Etonian Bear, or 'Edward Michael', as his mother likes to call him, hardly looks like the stuff of nightmares. He has an accent that would shatter glass and looks more like a well-intentioned Geography teacher than an action hero.

But anybody who has tuned into his Bear Grylls: Born Survivor series on the Discovery Channel knows exactly what we're talking about.