A relaxed Sir David Attenborough raised a glass of champagne to toast the 90th birthday of the widow of the man who founded the Wildfowl and Wetlands Trust (WWT).

The veteran nature broadcaster and naturalist was in Gloucestershire to help Lady Philippa Scott, the wife of the late Sir Peter Scott, celebrate her landmark birthday.

Sir David, 82, also took time to urge the human race to protect the natural world as he paid tribute to Sir Peter in front of more than 120 guests at Lady Scott's birthday bash at the WWT centre at Slimbridge.

As well as celebrating her birthday, Lady Scott, WWT honorary director, launched the latest edition of her book, The Art of Peter Scott, a volume of her late husband's paintings.

After discussing the book, Sir David, who presented the BBC's groundbreaking series Life on Earth, urged people to follow in the footsteps of Sir Peter – the only child of Antarctic explorer Robert Falcon Scott – and bring conservation to the fore.

Sir David said: "I believe in decades to come the name Scott will be revered even more round the world than it is today.

"The Scott partnership put conservation on the map at a time when conservation was not a word people understood, at least not in the natural history context.

"And if ever the world was in need of conservation, it is now. Unless the people of the world understand about the natural world, and we conserve and protect the natural world, the human race is in real trouble.

"And if, in fact, it is the case that they do those things, and it is the case that what survives of the natural world is seen to be deeply precious and essential to conserve, much of that realisation will be a legacy of the Scott legacy."

Sir Peter Scott founded the Severn Wildfowl Trust, now the Wildfowl and Wetlands Trust, in Slimbridge in 1948.

He went on to lead several ornithological expeditions worldwide, and became a television personality with his BBC natural history series Look, which ran from 1955 to 1981 and made him a household name. He died in 1989, aged 79.