Nat Geo Investigates

National Geographic, Friday, 10 p.m.

At 25 years, Explorer is the longest-running documentary series on television. Through hundreds of films, Explorer has provided its viewers a window on a changing world. The series has been able to document global change in a unique way.

Saturday Kitchen Series

Zee Khana Khazana, Friday, 7: 30 p.m.

When James Martin is in the kitchen, it is like being at a trendy catering college – albeit with a dishy private tutor. The cookery on Saturday Kitchen is well-judged – food that can be bought and cooked on the day, and grace the dinner table that night. In each episode, the energetic James plays host to guest chefs and celebrities. As they undergo a series of culinary challenges, will they be voted into ‘food heaven' or consigned to ‘food hell'?

Great Romances of the twentieth century

Fox History, Friday, 8 p.m.

Humphrey Bogart and Lauren Bacall fell in love at first sight on the set of Howard Hawks “To Have and Have Not” when the moody tough guy played opposite the 19-year-old, tall willowy blonde with the huskiest of voices. This was the prelude to a passionate love affair and one of the happiest marriages in tinseltown. Ingrid Bergman won the heart of Hollywood, but an illicit affair with Italian film director Roberto Rossellini shocked the world and almost ruined her career.