Sir David Attenborough almost died after he plunged "40 feet" off a cliff in the Lake District as a youngster.

Sir David Attenborough

Sir David Attenborough

The 89-year-old naturalist recalled the moment his life flashed before him when he went rock climbing up Walker's Gully - a mountain trail in the national park - lost his footing and slipped 15 metres down on to a small grass verge.

Asked if he's ever thought he was about to die, he said: "Once, yes once. I used to be a mad rock climber, I mean an obsessive rock climber and I fell off in the Lake District [at a place] called Walker's Gully and I came down about 30 or 40 feet... and I landed on a patch of grass hardly bigger than that [cushion] and I was absolutely sure I could have died."

And, as well as fearing his life was about to end during the ordeal, the legendary presenter also remembered being struck with guilt about how he'd let his parents down.

He explained: "I thought how ungrateful I was and what my parents would think. They'd spent all this time, looking after me and being nice to me and that was what their reward was. I felt desperately sorry that I'd let my parents down."

Meanwhile, the wildlife presenter may be set to turn 90 in five months' time, but shows no signs of slowing down.

Speaking about his retirement on 'Good Morning Britain' this morning (22.12.15), he said: "Well until I fail to do what I do and that's going to happen, something's got to go! And I don't know what it is, I've got new knees, I can go faster than I used to five years ago. That's a huge gift."