Kate Middleton's dark portrait painting by BP award winning artist Paul Emsley has become the best selling postcard in in the National Portrait Gallery shop. The painting showing a more serious side to the Duchess has sold over 3000 reproductions in the first weeks since it's unveiling on the 11 January. The portrait was commissioned by the Gallery with funds given by Sir Hugh Leggatt, in memory of Sir Denis Mahon, through the Art Fund.

The Duchess of Cambridge was involved in the selection process, from which artist Paul Emsley, the 2007 winner of the Gallery’s BP Portrait Award competition, was chosen by Director Sandy Nairne to paint her official portrait. The Duchess took part in an initial meeting to talk through the process of the painting. This was followed by two sittings, in May and June 2012, at the artist's studio in the West Country, England, and Kensington Palace. Emsley later made use of a series of photographs produced during the sittings. His subjects are frequently located against a dark background and emphasise ‘the singularity and silence of the form’, while utilising a meticulous technique of thin layers of oil paint and glazes.

Paul Emsley says: ‘The Duchess explained that she would like to be portrayed naturally - her natural self - as opposed to her official self. She struck me as enormously open and generous and a very warm person. After initially feeling it was going to be an unsmiling portrait I think it was the right choice in the end to have her smiling - that is really who she is.’ Despite the portrait not being well received by the press, the public seem to have taken to it in a big way.