shows on BBC Four

Two-part documentary, introduced and narrated by model train enthusiast James May, that follows a year inside Hornby Hobbies - an iconic British toymaker on the brink of collapse. But this is no ordinary business series - this is a series about model train and plane obsessives, both inside and outside the company, all of whom desperately need the company to survive.

This show offers a fascinating insight into the secret history of catching murderers as it looks at two centuries of breakthroughs that have changed the course of justice. Gabriel Weston looks at some of the most absorbing, and often gruesome, stories in the forensic casebook.

In this series, mathematician Dr Hannah Fry explores the mystery of maths. It underpins so much of our modern world that it's hard to imagine life without its technological advances, but where exactly does maths come from? Is it invented like a language or is it something discovered and part of the fabric of the universe? It's a question that some of the most eminent mathematical minds have been wrestling with. Dr Eleanor Knox from King's College London believes it's discovered, Prof Hiranya Peiris from University College London believes it's invented, while Prof Jim Gates from Brown University believes it's both, and Prof Brian Greene from Columbia University has no idea. The jury is very much divided. To investigate this question, Hannah goes head first down the fastest zip wire in the world to learn more about Newton's law of gravity, she paraglides to understand where the theory of maths and its practice application collide, and she travels to infinity and beyond to discover that some infinities are bigger than others.

Lucy Worsley explores how the history of three of Britain's founding national events are in fact carefully crafted mythologies. The Wars of the Roses, the Glorious Revolution and the creation of the British Raj are all revealed as carefully-constructed narratives created by the victors at the time and embellished by historians, novelists and film-makers ever since.Throughout the series, Lucy travels across Britain, the Netherlands and India to the palaces, battlefields and bed chambers where these stories were created and reinvented over the years. She also meets up with experts who shed further light on how these legends and mythologies have been woven together to create A Very British History.

Documentary series in which Lucy Worsley dispels the myths behind some of the key moments in British royal history.

Dr Lucy Worsley chronicles the birth of the whodunit in a new three-part series, A Very British Murder. Exploring how a spate of grisly killings in Regency London entered the national psyche, she'll show how the murder tale gradually became a staple of Victorian entertainment and helped to inspire the works of authors such as Charles Dickens, Arthur Conan Doyle and Agatha Christie.

Lucy Worsley reveals the myths and manipulations behind American history.

In this investigative three-part series for BBC Four, filmmaker Gillian Pachter re-examines the Ruth Ellis case. In July 1955, Ruth was the last woman to be hanged in Britain. Her crime: the cold-blooded murder of her lover David Blakely. It is a case that shocked the nation and still fascinates today. It has its place in ushering in the defence of diminished responsibility and the eventual abolishment of capital punishment. We all think we know the story, but why, when it was seemingly such an open-and-shut case, does it still divide opinion on whether Ruth Ellis got the justice she deserved? Gillian wants to find out.

In this mind-bending series, Jim Al-Khalili explores the vast range of size in the universe, from tiny atoms to gigantic, interconnected galaxies.

The Great British Photography Challenge follows world-famous photographer Rankin as he mentors the contestants, providing a unique masterclass in the art and craft of photography. Every shot counts as Rankin's 'students' build up to the task of creating and presenting a portfolio of their work, to be revealed at a climatic exhibition in the final episode. Although a winner is ultimately chosen, no-one is eliminated from the series, which takes a nurturing approach and embraces different perspectives as we follow all six throughout the process.