A picture of two princes: dual portrait of William and Harry goes on display

The first double portrait of Princes William and Harry has been unveiled at The National Portrait Gallery.

Titled 'Prince William and Prince Harry: a new portrait', the painting by Nicky Philipps depicts Prince Charles' two sons in "brotherly banter" in the library at Clarence House, their official London residence.

The artist had five sittings with the brothers over the course of six months from August 2008 – many of which took place at her studio – arranged around their army careers and other official engagements.

She thoroughly enjoyed working with William, 27, and his younger brother, who are both depicted wearing the uniform of the Household Cavalry.

"They were apprehensive to begin with, but they went along with everything," revealed the 45-year-old. "They were good company and very helpful."

"The pose was instinctive on their part, which I liked. Although I was commissioned to paint them in their official context, I hope I have also captured some of the brotherly banter characterised by the sitters."

The subjects of her work are also said to be pleased with the painting, which is being displayed in the museum's Contemporary Galleries alongside other royal portraits from the past century.