“When you go to Richmond to talk to him about an idea, there’s a certain nervousness because he’s a very decisive man and he says yes or no and quite quickly. I didn’t really know but I thought he would like it and he was unbelievably enthusiastic,” he explained.

“[Attenborough] said to me, ‘Look, I love doing new, and nobody’s done this, and I’ve never done this, so I really want to do it.’ But also, he totally agreed and was totally fired up with the promise that given the money, given the time, we could deliver things that would genuinely surprise people.”

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The producer added that Attenborough later agreed to appear on screen in the documentary and was like “a little boy” on set.

Fothergill continued: “He said a number of times to me over the last year or so, ‘God, that’s better than anything I’ve seen in the Serengeti.’ That’s extraordinary,” he said. “As we got through the process, producers and I realised that wouldn’t it be wonderful to have him on location?

“You know, he’s 96. We took him to Skomer Island, a remote island off Pembrokeshire, but he was, as always, he was like a little boy. Now he spends a lot of time in Richmond, you know, he’s doing his amazing work on his narrations, which he will continue to do, but he clearly can’t travel as much as he did so it was an enormous pleasure and a privilege to do it.”

The new series looks in close detail at the rich variety of wildlife habitats in the UK, from killer whales and golden eagles to “sinister woodland plants” that “take pollinating insects hostage”.