What’s more amazing: a 130ft dino or Attenborough’s eternal youth?

Whatever David attenborough is on, I want a bottle of it. the 89-yearold naturalist is as sprightly as a teenager. any more bounce in his step and he’d be on Strictly.

hunting for monster fossils in Attenborough And The Giant Dinosaur (BBC1), Sir David was skipping over the rocks of Patagonia, bending down agilely to pluck fragments of bone and shell from the earth, squatting on his haunches or even lying stretched out on the ground to examine remnants of dino-egg.

the argentine paleontologists, reconstructing the biggest sauropod skeleton ever discovered, couldn’t compete with his energy. he was constantly joking around — a side of his character familiar to camera crews who have worked with him over the decades, but rarely seen on screen.

Six scientists were wrestling with a fossilised vertebra the size of a small hatchback, struggling to stand it up. Sir David sauntered over and put out a hand, as if to shove it over, before bursting into mischievous laughter.

When one of the experts explained that the sheer bulk of the titanosaur’s hip bones suggested that it swung its tail to help it walk, Sir David joked: ‘I must try that some time’ — and wiggled his behind like Marilyn Monroe.

Part of his joie de vivre comes from the satisfaction he feels in talking about dinosaur excavations on television. Most of his career has been devoted to filming wildlife, but fossils were his first love.

as a boy, he searched for ammonites and trilobites in the Leicestershire woods. he has never lost that youthful enthusiasm. ‘I’m fascinated by dinosaurs,’ he said at the outset of the show.

his excitement is transmitted through the screen. You might think it’s hard to be interested in an animal that died 101,600,000 years ago, but Sir David made us feel we were on safari beside him, watching it forage and feed.

this titanosaur weighed 70 tons and had a neck so long it could nibble the leaves of monkey puzzle trees 130ft off the ground. to sustain its vast bulk, it had no time to chew its food and so swallowed the foliage whole — 1,500lb of it every day, enough to fill a skip to overflowing.

the sheer scale of its bones was awesome — up to 25ft long, the size of steel girders. the archaeologists started work, not with trowels and brushes, but with pneumatic drills and mechanical diggers.

It was the eggs, preserved for 100 million years under volcanic ash, that gave us the clearest clue to how the creature must have looked. One had been crushed and slowly turned to stone when the hatchling inside was about to be born.

a patch of skin had survived through the aeons and it looked like nothing found on earth today — suggestive of leather covered with fish scales.

Sir David was agog. and that meant we were agog, too.

James May is also a genuine enthusiast, but as he conducted a long, worthy and very dull comparison of fuel consumption in american and Japanese saloon cars circa 1973, nobody was agog. Cars Of The People (BBC2) celebrates ordinary motors, the sort that families could afford. Starting with the austin Seven in the thirties, he worked his way up to the allegro half a century later.

James was bemoaning the death of the British car industry, which he attributed quite seriously to the fact we won the war: because the Germans and Japanese were forbidden to re-arm, he said, all their repressed military ambition was channelled into the automobile industry.

as a theory, that is dodgy at best. But James was determined to ignore a much more obvious explanation. he took a swipe at complacent designers. he grumbled about inefficient management. he tutted over the oil crisis.

When it came to the endless strikes at British Leyland, however, and the closed shops, the workers paid to sleep on the factory floor, the blackmailing shop stewards and the picket line violence, all James could do was bewail ‘the bloody class system’.

apparently, even 40 years on, it is forbidden on BBC2 ever to criticise the unions.