Celia Hatton

The Russian Foreign Ministry has rejected the findings, calling them tasteless fairy tales.

The BBC's Tom Simons told Janat Jalil more about the case.

And it later emerged that the Novichok in this perfume bottle could have potentially killed thousands of people.

So tell us what this report has found today.

What is it saying today?

And the big question for a lot of people will be what lessons can be learned to prevent another such attack?

Because it isn't the first time that there's been a nerve agent poisoning in Britain.

Tom Simons.

How does a local outbreak of disease morph into a global pandemic?

It's a difficult and sometimes controversial question to answer, as we learned from COVID-19.

But researchers hope that understanding illnesses of the past can help us with the outbreaks of the future.

And new evidence suggests that one of the deadliest pandemics in world history, the Black Death, spread in part because of a volcanic eruption.

Our science correspondent Helen Briggs reports.

The Black Death is regarded as one of the largest human disasters in history, killing more than half the population in parts of Europe in the mid-14th century.

Scholars have pored over the question of how the bacterial disease spread by rats and their fleas was carried from its heartland in Central Asia to Europe.

Now, climatic clues preserved in tree rings suggest a volcanic eruption might have been part of the picture.

Researchers at the University of Cambridge say volcanic activity caused a shock downturn in temperatures, which triggered crop failure.

To avert famine, Italian city-states were forced to import grain from north of the Black Sea, and with that came plague-carrying fleas.

Dr. Martin Bork from Germany's Leibniz Institute for the History and Culture of Eastern Europe helped piece together the clues.

The experts say this perfect storm of climate change, famine and trade offers a reminder of how, in a globalised and warmer world, diseases can emerge and spread.