From the death penalty, to laws against homosexuality, Britain's criminal justice system has undergone momentous change in the last 70 years.

In this Timewatch guide to Crime and Punishment, presenter Gabriel Weston examines how television has played a crucial role in documenting these seismic shifts in British law and policing.

Looking back through the Timewatch back catalogue of documentaries and a host of BBC archive rarities, Gabriel discovers how historians and filmmakers have not only chronicled these profound changes in law but also managed to shape public opinion.

By highlighting miscarriages of justice, like that of the wrongful imprisonment of the Birmingham Six, or by shining a spotlight on other issues of corruption and damning flaws in police procedures, Gabriel finds that television actually became a powerful agent for change.

Less than 100 years ago, the British ruled a quarter of the planet and one in five of the global population. Once, people were proud to call themselves imperialists, but now, to many, that seems like a badge of shame.

In this Timewatch guide, David Olusoga examines not whether the British Empire was a force for good or ill, but rather how it has been portrayed on British television over the last 70 years. Drawing on decades of the documentary series Timewatch, plus many other gems from the BBC archive, David sees how Britain's Caribbean colonies grew rich on slave labour, how chaos gripped India post-independence, and how Africa was plundered for her mineral wealth.

David investigates how film-makers through the years have represented the actions and legacy of Britain's period as the world's ultimate superpower. It used to be said that the sun would never set on the British Empire - now, long after it's gone, the arguments surrounding it are very far from being settled.

From earthquakes to tsunamis to volcanic eruptions, natural disasters are both terrifying and fascinating - providing endless fresh material for documentary makers. But how well do disaster documentaries keep pace with the scientific theories that advance every day?

To try and answer that question, Professor Danielle George is plunging into five decades of BBC archive. What she uncovers provides an extraordinary insight into one of the fastest moving branches of knowledge. From the legendary loss of Atlantis to the eruption that destroyed Pompeii, Danielle reveals how film-makers have changed their approach again and again in the light of new scientific theories.

While we rarely associate Britain with major natural disaster, at the end of the programme Danielle brings us close to home, exploring programmes which suggest that 400 years ago Britain was hit by a tidal wave that killed hundreds of people, and that an even bigger tsunami could threaten us again.

In recent years the world has become an unsettling place, from the mass movements of refugees to political upheaval, both in this country and abroad.

Disturbingly, history shows that it's at unsettled times like this that dictators can rise - leaders who promise they can solve every problem, if only they're granted supreme power. David Olusoga examines fifty years of BBC documentary archives to try and discover why dictators can have such a powerful appeal. David uncovers the surprising optimism felt by the West towards men like Gaddafi and Mugabe early in their regimes, and examines the events that turned this optimism into horror. He questions why such men continue to fascinate us regardless of their actions, and asks whether, especially in an age of mass media, our fascination has fed their power