A long-lost painting authenticated as the work of Leonardo da Vinci was sold for a world record price of $450m in a dramatic auction in New York in 2017. The price stunned the art world and created a storm of attention for a painting that had only been rediscovered in 2005.
The art historian and writer Ben Lewis tells Rachel Humphreys of his quest to chart the remarkable story of the painting, now believed to be in the collection of the Saudi crown prince, Mohammed bin Salman.