This week, how more than one billion people living in India were given a unique digital ID during the world's largest biometric project. The Aadhaar scheme was launched in 2009 but it wasn't without controversy. Our guest, digital identity expert Dr Edgar Whitley, tells us about the history of ID schemes around the world.

Plus, the Spanish doctor whose pioneering surgery helped millions of people to get rid of their glasses and see more clearly. And why East Germany's thirst for caffeine in the 1980s led to an unusual collaboration with Vietnam.

Also, the story behind one of the most famous royal photographs ever taken – Princess Diana sitting alone on a bench in front of the Taj Mahal in 1992. The man who took the image tells us more.

And finally, how a Ghanaian athlete, Alice Annum, earned the nickname ‘Baby Jet’ after her medal-winning success in the 1970 Commonwealth Games.

Contributors: Nandan Nilekani - former chairman of the Unique Identification Authority of India Dr Edgar Whitley - digital identity expert at the London School of Economics Dr Carmen Barraquer Coll – daughter of ophthalmologist Jose Ignacio Barraquer Moner Siegfried Kaulfuß – East German official in charge of coffee production in Vietnam Anwar Hussein – royal photographer Alice Annum – retired Ghanaian athlete

(Photo: Scanning fingerprints for Aadhaar registration. Credit: David Talukdar/NurPhoto via Getty Images)