The dress code was ‘black tie with a hint of sparkle’ And on her first official engagement of the year, the Duchess of Cambridge certainly stuck to the sparkle Around her neck was a priceless diamond necklace on loan from the Queen. The Nizam of Hyderabad necklace was given to Her Majesty as a gift when she married in November 1947.Wearing a midnight blue Jenny Packham evening gown – plain to show off the beauty of her diamonds – Kate Middleton walked up a set of stairs encrusted in gold glitter in honour of the occasion with a hint of a tan courtesy of her recent holiday with Prince George to Mustique The Duchess was tonight attending the black tie Portrait Gala 2014 at the National Portrait Gallery in London in her role as patron.She met with a selection of guests during a reception before attending the Gala Dinner. Those attending the event included legendary photographer David Bailey, Olympic Gold medallist Katherine Grainger, transvestite potter Grayson Perry, actor Alan Rickman and artist Jonathan Yeo Mr Perry recently collected his CBE from Prince Charles at Buckingham Palace wearing what he referred to as his ‘Italian mother of the bride outfit’.In doing so he became the first man to ever do so dressed as a woman. Fortunately the palace has become something progressive of late and his choice of attire was described as ‘entirely appropriately’ by the Queen’s spokesman Shortly before dinner, the Duchess was introduced to Mr Perry, resplendent in a white trimmed gown and black heels who said he had been told he was ‘channelling his inner peeress’ As the Duchess and the artist were introduced onlookers jokingly remarked that ‘the girl wearing rocks had met the guy wearing frocks’.The pair chatted for several minutes before the Duchess was escorted by Sandy Nairne, the director of the National Portrait Gallery to view a display of 200 mystery portrait postcards created anonymously for the gala by a selection of well known artists including Perry, Julian Opie and Alex Katz. The postcards will be sold as part of the fundraising effort Other guests included actress Elizabeth Hurley who wore a gold lame evening gown and white fur stole Understandably, the Duchess has only undertaken a handful of engagements since the birth of her son, Prince George, last July and her presence at any charity event is considered a huge fundraising draw.In a short speech, the Duchess said : ‘I just wanted to say how delighted I am to be here this evening to celebrate the fantastic work of The National Portrait Gallery ‘The Gallery’s achievements are exceptional. They hold the most extensive collection of portraits in the world, and their unique and brilliant exhibitions never fail to inspire us all But, it is more than simply a world renowned visitor’s attraction – the Gallery’s outreach and research programmes makes it one of the leading centres for the important study into Portraiture.’I simply could not be more proud to be its Patron ‘Thank you for being here tonight and showing your support. I hope that you all have a wonderful evening. The necklace worn by Kate to the Gala is still occasionally worn by the Queen today. The Nizam of Hyderabad asked the Queen to choose two pieces from Cartier to mark her wedding – and the then Princess Elizabeth chose a tiara and a necklace based on an English rose The tiara was subsequently broken up to create other pieces but the necklace remains intact.The Nizam of Hyderabad necklace was originally created by Cartier in 1930s. It consists of a long chain of 38 diamonds (reduced from the original 46) with a diamond-encrusted snap. The centre of the necklace is pave-set with detachable double-drop pendant 13 emerald-cut diamonds and a pear-shaped drop The original necklace consisted of eight double-drop and three triple-drop pendants. However, nine of the pendants (all eight double-drop and the larger of the triple-drop pendants) were later removed and sold separately.