Kate Middleton and Prince William were at the National Portrait Gallery, to unveil the first official portrait of the Duchess of Cambridge.

A pregnant Kate Middleton has been ordered to rest since she was discharged from King Edward VII Hospital in early December, having been diagnosed with acute morning sickness. However, Catherine Middleton looked as fresh and beautiful as ever for her first portrait unveiling, dressed in a burgundy outfit by Whistles. The gown was paired with black court shoes.

The Duchess's portrait was painted by Paul Emsley, the 2007 winner of the Gallery's BP Portrait Award competition. The sitting took place at Emsley's studio in Bradford on Avon and at Kensington Palace, and Kate Middleton is reportedly delighted with the result, calling it "amazing" and "brilliant".

There has been criticism too, with Emsley admitting it was always going to be difficult to paint Kate Middleton's likeness, given her immense popularity.

"A person whose image is so pervasive, for an artist it is really difficult to go beyond that and find something which is original," he explained, "You have to rely on your technique and your artistic instincts to do that and I hope I've succeeded."

The National Portrait Gallery's painting of its patron was commissioned with the support of Sir Hugh Leggatt, in memory of Sir Denis Mahon, through the Art Fund. Kate Middleton, who recently celebrated her 31st birthday, is a patron of the Gallery and her first official solo engagement was the opening of the Lucian Freud Portraits in February 2012.

Check out photographs of Kate Middleton and Prince William at the event...

Britain's Catherine, Duchess of Cambridge attends a private viewing of her new official portrait by Glasgow-born artist Paul Emsley at the National Portrait Gallery in LondonReuters
Glasgow-born artist Paul Emsley greets Britain's Prince William during a private viewing of his new official portrait of Catherine, Duchess of Cambridge, at the National Portrait Gallery in LondonReuters
Catherine, Duchess of Cambridge, attends a private viewing of her new official portrait by Glasgow-born artist Paul Emsley at the National Portrait Gallery in LondonReuters
Catherine, Duchess of Cambridge smiles at a private viewing of her new official portraitReuters
Glasgow-born artist Paul Emsley next to his portrait of Britain's Catherine, Duchess of CambridgeReuters
Catherine, Duchess of Cambridge, leaves the National Portrait Gallery with Prince William, after viewing her new official portraitReuters
Journalists crowd around the first official portrait of Britain's Catherine, Duchess of Cambridge, at the National Portrait Gallery in central LondonReuters