Hidden Treasures of the National Trust Season 4 Episode release dates & where to watch

1. A New Agatha Christie Mystery

The homes of two literary giants reveal personal treasures and the real people behind the pages.

2. The Duke, His Wife and Their Lover

Two great country houses reveal stories of extravagant Grand Tours, royal luxury and one of Georgian society's most scandalous relationships.

3. Puffins and Pilgrims

Preserving the legacy of St Cuthbert and a colony of breeding seabirds on the remote Farne Islands. And experts in Wales race to save a fragile Bible that shaped Welsh culture.

4. Collectomania

Caring for the curious collections at two of the National Trust's most unusual houses, from a boy's suit of samurai armour to stuffed birds and a living collection of rare sheep.

5. Bobbins and Hobbit Holes

Exploring workers' lives in the Industrial Revolution: a rare contract of a boy tied to a cotton mill is conserved, and final touches are made to Kinver Edge's rock houses.

6. Top Secret Seedlings Finale

Preserving garden designer Gertrude Jekyll's legacy at one of the National Trust's newest properties, and at Nymans, celebrating the flamboyant set designer Oliver Messel.