BBC Four HD Tuesday

Tim Dunn visits the Ffestiniog railway in north Wales, originally built to transport slate from mountain to coast and learns about Amsterdam Centraal

Chris Beardshaw visits Dumfries and Galloway to learn about plant hunters who found new species in Essex

Audrey moves out of Grantleigh Manor, and Richard and his mother move in, disappointing the former resident with their new ways. Comedy, starring Penelope Keith and Peter Bowles

Hyacinth once again tries to rescue Richard from social obscurity with a plan to turn him into an executive - but he proves far from enthusiastic

The actor explores some of the most important archaeological finds in Ireland's history, answering questions about the Celts, and what it means to be Irish

Japanese and US veterans reflect on the impact of the suicide missions during the Second World War that killed thousands of Japanese airmen and Allied military personnel

Professor Brian Cox joins the team to explore the mysteries of black holes in light of the James Webb Space Telescope's most exciting new observations

Scientists conducting research into weather on other planets, who have discovered strange phenomena including rains of precious stones, supersonic winds and world-spanning storms

Artist and critic Matt Collings explores the world of mathematical equations, looking at some of the most famous examples, including Einstein's E=mc2 and Newton's laws of gravity

Chris Beardshaw visits Dumfries and Galloway to learn about plant hunters who found new species in Essex

The actor explores some of the most important archaeological finds in Ireland's history, answering questions about the Celts, and what it means to be Irish