Broadcast icon Attenborough gives backing to environmental protesters

In 2017, it was reported by the Sunday Times newspaper that demand for online streaming of an episode of his series Blue Planet II was so heavy in China that it drew around 80 million viewers and temporarily slowed down the country's internet.

Attenborough now confines his involvement to writing and voicing the script, and says broadcasting to such a diverse audience, the key thing is to keep it simple.

"These days my contribution is the words, and the fewer the better," he said. "Just keep it simple. You don't need to use adjectives, people can see things for themselves. The more straight-forward it is, the more effective it is."

The full effectiveness of the combination of carefully chosen words and stunningly evocative pictures was made apparent by the impact of Blue Planet II's coverage of the issue of plastic pollution, which established the subject as a major international talking point.

"I've not seen anything like it," said Jonny Keeling, executive producer of Seven Worlds One Planet and a long-term member of the BBC's Bristol-based Natural History Unit. "In the past I've worked on things where a couple of months later, something had an impact on a smaller group of people, but this was within weeks and at a national and international level. It impacted on the general public, major companies and people in corridors of power."

Such was its impact on the audience in China that when then-British prime minister Theresa May met President Xi Jinping in 2018, she presented him with a DVD boxed set of the series signed by Attenborough. Both at home and abroad, his message was being heard and having an impact at the very highest level.

Attenborough admitted to having been stunned by the reception that episode received, and the political waves its message created, not least because he had been saying similar things in his programs for decades.

"It had an impact greater than anything else I've ever known, but I've been saying that sort of thing for 30 or 40 years but nobody took a blind bit of notice before," he said.

"I went back and looked at the end of my (1979) series Life on Earth, and at the end I went off on a two-minute piece about responsibility to the planet. The thing is, you never know when you're going to say something that will ring a bell with people. If you go back years, you'll see the messages I've done in my series are exactly the same in length, detail and urgency. I can look back at them today and I wouldn't change a syllable of them.

"What has changed is the social environment — it's quite extraordinary, there's been a huge change in world opinion in the last five years, people of all ages in all nations have said 'this is terrible, look at what's happening'. The bell we rang in Blue Planet II just happened to coincide with some wider public sensitivity, so we hope we can do the same with this series."