Actor Brian Blessed is famous for so many things - his voice, his beard and, of course, his trips up Everest. He was policeman in the classic TV cop show Z Cars, armoured from head-to-foot in Robin Hood Prince of Thieves, wearing a Viking helmet in Flash Gordon, and a crown in Blackadder - but in the flesh he is even larger-then-life than the characters he has played on stage and screen.

Whether he is swimming with piranhas in the Amazon, climbing yet another mountain or enthusiastically getting involved in numerous charities, at 71 this bear of a man remains a real powerhouse.

Currently his professional diary is packed. Brian is touring in a production of Peter And The Wolf, acting in a feature film in Hungary, filming As You Like It with Kenneth Branagh and providing the voices for characters in animated films.

Away from stage and screen, Brian is planning to climb a mountain called Sangai in the Himalayas and "hoping to fit in another couple of expeditions before Christmas."

As if all that isn't enough, he is also training to go into space, planning a major sea voyage and, in between, helps his wife look after the 2,500 animals on their farm in Surrey.

You sense that this man throws himself into everything 100 per cent - and that includes his rigorous fitness regime of running eight miles-a-day and weight-training for two-and-a half hours.

"I've got a figure like a GI, or a gorilla, because of the fitness regime I did when I served my National Service at Upper Heyford and trained with the Americans on the airbase. I think my sense of adventure all stems from there," he explained.

"I have also just accepted an offer to speak at the Oxford Union where I used to teach amateur dramatics. I have very fond memories of Oxford," he said.

In fact his experiences in Oxford alone would fill a small book.

"I did my National Service here in the 1950s and if there was any doubt about the power of the Americans you just had to come to the airbase.

"There we were in our scratchy underwear eating porridge while the Yanks swanned about in linen drinking litres of orange juice and eating pancakes. It was just a different world," Brian recalls.

"We hated National Service at the time because the Second World War was over and we couldn't see the point. I was doing what I wanted, working in the theatre, when I was drafted.

"And I have always had a deformed right foot so didn't think I'd get in. People used to make all sorts of things up to get out of it but they thought I was quite strong so let me in anyway.

"I remember one guy waiting to be seen who had one eye going one way and one eye the other. He obviously didn't get in.

"I bumped into him later on and his eyes were perfectly normal. He said he could make his eyes do that for hours," he remembers, howling with laughter.

"I was 17 stone then, and I remember this bully who used to beat up the Americans when he got drunk on Saturday nights.

"He picked on me one day in the canteen with his two henchmen by his side and assumed that, because I was into amateur dramatics, that I was a poof and gobbed in my food. That was his first mistake," Brian growled.

"Little did he know I used to be South Yorkshire's boxing champion. I tore him apart," he roared.

"It wasn't pretty, I can tell you. Of course the Yanks were hugely grateful and said they'd make it up to me by taking me to meet Big Bertha. I told them I was a virgin and really didn't want to pay for sex. But they insisted, and said that there was one condition - I had to be blindfolded.

"So they led me off and took me into a building before turning on the lights. Then they leant me against something and I felt cold metal all down my back.

"When they took my blindfold off I was leaning on an H-bomb - Big Bertha - which could have taken out half of Europe!

"Yes, Upper Heyford was a legendary place," he added, pleased with this memory.

Speaking of Oxford

"I always loved the idea of Oxford and university. I'd managed to get a scholarship to the Bristol Old Vic because I was good at acting, but I left school at 14 when my father was in a mining accident, so never had the opportunity to go to university. But now I'll be speaking at Oxford.

"People sometimes complain that Oxford is too flat, but I always tell them its mountains are its skies."

We are back to mountains again, which play a huge part in Brian's life. In fact, if he is not on stage or in front of a camera, chances are you will find him halfway up some previously unexplored peak.

For a 71-year-old this appears a staggering feat, but Brian thinks otherwise.

"People always ask me if it is dangerous and I always reply that the greatest danger in life is not taking on the adventure."

But don't his expeditions cost a lot of money?

"Yes, but I do a lot of them for charity, raising money along the way, or they are filmed," he said.

His exploration of Venezuela's Lost World, for example, was televised.

But don't think land-based adventures are enough for Brian. Apart from his sea quests - he plans to recreate Ulysses' journey around the globe, as well as exploring the bottom of the sea around Japan - he has also been training with Russian astronauts and is earnest in his discussion of space being the future.

The final frontier?

"Space is the key to the new millennium and we have got to get into space. If you think about it we are all astronauts on planet Earth, but we need a British space programme and the race is on," he said, before expanding on sustainable energy, rocket ranges, overpopulation, Mars Direct and mother Earth impregnating the solar system.

That the Russians found he had the fitness of a man 30 years younger pleased him enormously - something to do with his big veins and large lungs.

All this exploring doesn't take away from his acting, which still plays a huge part in his life.

"Branagh asked me the other day if I was still on their side, and of course I am.

"I still think that acting is one of the hardest jobs in the world because everything - your eyes, brains, heart and soul are judged," he said. " And 99 per cent of the time you are shot down and criticised and have to find the courage to appear again.

"It takes great courage to be an actor - and I am speaking as an explorer. But as Shakespeare said - acting is holding the mirror up to life, and adventure IS life. Everest is life. There is a huge difference.

"Even a first night at Stratford-on-Avon or The National cannot compare to the immense experience of ascending the flanks of Everest or reaching the North Pole.

Travels in Mongolia

"Actors are very boring when they talk about acting - if you're an actor, good, bad or indifferent, you must do it, you feel you have no choice. It is a must. But I love adventure more."

And then he's off again, this time on one of his recent travels to Mongolia, where for 50 days, all he saw were camels, wolves and bears, jungles and, of course, mountains.

"There is so much left to see. Did you know that one-third of Canada has only been seen by helicopter, or that there are mountains in Russia that are still unexplored. And, of course, the oceans are still largely an unknown."

Only someone with this much energy and zest for life could feed such an addiction for exploration.

So how does his wife, actress Hildegard Neil, cope, and does she ever get to see him?

"Well yes, quite a lot!" he laughs. "Expeditions are actually quite short."

"But where were we? Oh yes, I love adventure but that is adventure of all kinds whether its going swimming in the Amazon or going that extra yard on a Zimmer frame.

"Everyone has got something that no one else has got - they just need to be able to produce it, rather than worrying about their pension."