Everyone’s favourite nature wiz Sir David Attenborough went through two separate gruelling knee operations to keep on making great television documentaries – and he doesn’t plan on throwing in the towel any time soon.

Sir David, who will be 90 in May, told the Daily Mail Weekend magazine: “I had one done. They [the doctors] weren’t keen on doing both at the same time, which I would have liked because I was in my eighties. They don’t want to keep you on anaesthetic for that long. It was a nasty business.

“Not fun. I thought, ‘I’m not going through that again.’ But then the other one started playing up and I realised that if I wanted to go on making programmes I’d better be able to walk.

“Now I can walk for an hour. I shall be going off to Patagonia in a couple of weeks where we’re doing a film on a huge dinosaur that’s being excavated.”

Previously, David could only hobble around for a few yards as his old knees were unable to support him.

The much-loved natural world presenter, whose shows include The Blue Planet, Planet Earth and Frozen Planet along with a new series The Hunt, said: “I’m doing what I’ve done for the past 30 years. It’s only the fun that keeps me going. If I didn’t enjoy it I would stop. I’ve got a pension.”

Sir David politely dismissed a comment by outspoken adventurer Bear Grylls, 41, that Sir David’s personal style is “a bit dry” for today’s young viewers and that it “needs that adventure”.

Sir David said: “The natural world is wonderful enough. You don’t have to distort anything.

“What’s out there is so beautiful, so absorbing and so stunning, if you present it honestly there’s no need to over-sentimentalise it, no need to make it more awesome than it is. Let it speak for itself. This world is good enough for me, thanks.”

The Hunt begins on BBC1 later this month.