She was a serene force of nature. And she never wavered in her mission to help the animals to which she dedicated her life.

When I interviewed Dame Jane Goodall last year, she exuded calm, even as she pressed home to me that a great extinction crisis was facing our planet.

Over a slightly blurry video call, I could see her toy monkey, Mr H, behind her.

That toy was given to her nearly 30 years ago by a friend. Dr Goodall, who was 90 years old when we spoke, was still travelling the world with Mr H at her side.

Researchers I've spoken to this evening, whose work Dr Goodall inspired, or who were simply inspired by her energy, are in shock at her death aged 91.

Professor Cat Hobaiter, from the University of St Andrews, who has worked with Chimpanzees - studying their communication - for more than 15 years, told me that one reason Dr Goodall had such an impact was that "she gave up doing what she loved - spending time with her beloved chimpanzees - to tirelessly travel the world and share her passion with everyone she met."

In the many years that Jane Goodall observed and studied chimpanzees, she revolutionised our understanding of our closest primate cousins.

Key to her groundbreaking discoveries were her curiosity and ability - quietly - to observe.