In August 1888 Vincent van Gogh wrote to his brother Theo of his plan to paint sunflowers in a dozen panels. He planned the series as 'a symphony in blue and yellow'.

Lucrezia Walker, Freelance Lecturer at the National Gallery, talks about the significance of the 'Sunflower' series in exploring Van Gogh as an artist.

The lecture, 'Van Gogh: Sunflowers, Letters & Life' was held as part of the Gallery's 2014 display 'The Sunflowers', which witnessed the rare reunion of two of Van Gogh's famous 'Sunflower' masterpieces.

To find out more, visit: http://www.nationalgallery.org.uk/whats-on/exhibitions/the-sunflowers