Sir David Attenborough has said he is more optimistic than ever about the future of the planet after a “worldwide shift” in attitudes towards the the natural world.

The naturalist and broadcaster said there were “signs of hope” and that countries that had previously been skeptical about conservation were starting to change their attitudes.

In a special event at the Edinburgh International Television Festival to mark 60 years of the Natural History Unit at BBC Studios, Sir David, 91, said: "I spend a lot of time wringing my hands and saying how dreadful it is, and how this forest has been obliterated, and that sea has been polluted and whatever."

But he went on: "I am encouraged more than I have been, somehow."

Asked by what had heartened him over the past five years in terms of our relationship with the natural world, Sir David used the Paris climate change agreement between nearly 200 countries as an example.