Bear Grylls has spoken ahead of his ITV show, Bear's Mission with Anthony Joshua, which is on at 9.00pm tonight

In the boxing ring, world heavyweight champion Anthony Joshua is unbeaten in his 19 professional fights – but how will he fare when he tested his mettle against TV’s top adventurer Bear Grylls?

Tonight in a one-off ITV documentary, survivalist Bear, 43 challenges the boxer to embrace the great outdoors, confronting his fear of heights, sleeping under the stars and chowing down on tasty maggots.

We caught up with Bear Grylls to find out whether Anthony Joshua came out fighting or threw in the towel…

So, Bear, were you excited when you heard Anthony was going to be your latest ‘opponent’?

“Taking a home-grown legend like AJ on such an iconic British journey was a privilege. I’ve had incredible times with celebrities on Mission Survive, so the chance to take AJ on an adventure was special.”

What did you make of Anthony before you started the trip?

“He’s the ultimate survivor, the ultimate finisher, but where we were going, he would require a whole different set of survival skills!”

Where did you take him?

“To ‘Commando Ridge’ in Cornwall. It’s one of the UK’s most notorious climbing faces, where the Royal Marines have trained for decades.”

What was his hardest challenge?

“A textbook military challenge every commando dreads: a 100ft rope crossing above a deep gorge, 200ft above the sea. However fit you are, when you throw in the adrenaline and fear as well as the physicality of this kind of challenge, it’s hard.”

Are there any similarities between his training and yours?

“Commandos have a saying: ‘If it ain’t raining, it ain’t training.’ AJ knows this from boxing – train hard, fight easy. You see the knockout punch, but the fight is won in the hard yards of early morning training.”

What sort of snacks did you cook up for Anthony on the trip?

“To teach AJ a valuable survival lesson, I left a sheep’s leg for a few days to rot. It had flies and maggots on it, but there’s more protein in maggots than beef! Because the bone is well protected, you can smash it, get to the marrow inside and fry it up – it’s nature’s sausage!”

What is the enduring appeal of Bear’s Mission with…?

“It works well because we get to see celebrities uncovered and hear their triumphs and failures, their struggles and motivations, all wrapped around a great journey. It’s fitting I took AJ to a place where marines train as AJ is one man I would like fighting alongside me. He’s got the heart of a lion and the courage to match.”