Rating: Five out of five stars

David Attenborough still has dreams about that day he was befriended by a family of mountain gorillas in the rainforests of Rwanda.

One of the most famous moments ever captured for television was also a defining incident in a uniquely illustrious career. 

Sir David, who will be 100 years old next week, had been controller of BBC1 and BBC2, overseen the launch of colour television, and turned down the role of Director General.

But it was that brief sequence of him laughing and chatting to camera, while a gorilla baby sat on his chest and its doting mother prodded his face with her fingers, that encapsulates how we will always think of him.

The story of how the camera team missed most of the 15-minute encounter, and how the Rwandan army almost confiscated what footage remained, has been told many times. 

But it was put into the context of his whole life, in Making Life On Earth: Attenborough's Greatest Adventure.

Sitting at a desk and reading from his diaries, Sir David looks and sounds remarkably well for a chap just a fortnight away from his centenary.

But as generous excerpts from the 1979 series reminded us, he always did look young for his age - 52 at the time, but more like a man in his 30s, even on that day in the Grand Canyon when he was suffering from an unfortunate allergy to mule hide, which made his eyes blow up like puffer fish.

His mischievous sense of humour, as I've been fortunate enough to discover during numerous interviews with him, is never far from the surface. 

Waiting in an armchair for filming to begin, he grinned and waved to familiar faces, and played up to the photographer, with his chin on his fist: 'Would you like a pensive shot? I'm very good on that.'

Then he pretended to chide himself: 'Now sit up straight. Settle down!'

Many of the original Life On Earth team, from the secretaries to the wildlife cameramen, were queuing up to share their memories, and all of them talked about his diplomatic charm.

Part of that lies in his modesty. Explaining why he turned down the D-G's job, he said, 'I don't have political skills - I may know about birds of paradise but I don't know about Prime Ministers.'

Sitting behind a desk, he added, 'wasn't nearly so much fun' as travelling the world to study rare and exotic animals - a sentiment millions shared when Life On Earth first aired, filling us with wanderlust and a yearning to go on safari.

Though he's as busy as ever on wildlife spectaculars, his voice-overs are scripted, which means his gift as an off-the-cuff raconteur is less obvious. 

Here, it came to the fore. He's never lost for the evocative phrase.

'Extraordinary,' he said, remembering those gorillas again. 'A breathtaking experience . . . one of the most privileged moments of my life.'