Why is this painting of a felt hat nicknamed The Straw Hat_ _ Rubens's 'Portrait of Susanna Lunden'

Peter Paul Rubens was one of the best portrait painters in the history of art. His 'Portrait of Susanna Lunden (?) ('Le Chapeau de Paille')' has inspired artists for centuries.

There are various stories about how the painting came to be known as 'Le Chapeau de Paille' (French for 'The Straw Hat') - a strange title given that the hat Susanna is wearing is made of felt.

Bart Cornelis, Curator of Dutch and Flemish Paintings, tells us the story of this influential painting and its confusing name.