Kate reprised another frock from the royal walk-in for tonight’s reception at the Royal Academy.
She brought back the Roksanda Ilincic ‘Peridot’ dress, above we see the Duchess being welcomed to the Academy by its President, Christopher Le Brun.
The occasion was a reception for the GREAT Campaign, an effort to capitalize on the worldwide exposure Britain is receiving from the Olympic and Paralympic Games.
The hope is to create tangible benefits from that exposure, in areas like tourism and exporting of goods.
A number of celebrities were in attendance this evening, including Stella McCartney, supermodel Lily Cole, designer Vivienne Westwood, and rock star Roger Daltrey. Below, the Duchess with Ms. McCartney. 
Below we see the Duchess and Mr. Le Brun from another angle, Prime Minister David Cameron is on the far right.
CNN’s David Wilkinson shared this photo of Kate chatting with guests, you can see the back of the frock.
David Wilkinson, CNN Twitter Feed
These product images better show the waist detailing front and back.
For those who may not remember last summer’s North American Tour, Kate initially wore the dress for her arrival in Los Angeles last July. Another look at it front and back, with thanks to Rebecca English of the Daily Mail for graciously sharing these via Twitter.
Here is how the dress was described when originally available for purchase:
Light blue grey. Draped neck to one side. Cap sleeves. Pleats down from drape neck to waist band. Pleated skirt. White tulle neckline and cuff trim. Centre back pleats. Small pleated panels from back waist band. Exposed centre back zip. Beige grosgrain front tie.
These are a tighter shot of Kate’s beaded bag. The clutch remains a UFO (Unidentified Fashion Object.)
We previously saw Kate carry the bag with the Roland Mouret ‘Lombard’ gown, the event was a private dinner at Claridge’s.
Kate paired the dress with a new pair of shoes from LK Bennett, the Harper.
Kate wore the Harper in taupe suede, it comes in a variety of colors. The shoe has a hidden platform, a 110 mm heel (about 4.5″), and a rounded toe; it is currently selling for £195, roughly $275 USD at today’s exchange rates.
The Duchess wore her hair in an updo, adding a touch of elegance to the ensemble.
Those photos also nicely show the custom Kiki McDonough blue topaz and diamond earrings we have seen Kate wearing on several occasions.
The Duchess flew solo for this event. Following this morning’s Equestrian events. More on the young royals’ efforts during this high-profile time from the Daily Mail:
Culture Secretary Jeremy Hunt added: ‘I was just watching the men’s gymnastics in front of Prince Harry and Prince William so I’ve gone from the Duke to the Duchess.
‘What the royal family are brilliant at doing is showing we have the traditions but also we embrace the future.
We’ll see you again tomorrow when Kate, William, and Harry return to Greenwich for the third, and final day of Equestrian competition. The trio is also slated to visit Team GB House at some point tomorrow. We’ll leave you with this photo of the Duchess leaving the reception.
Anne
Wednesday 1st of August 2012
A very elegant look, and like others here, I like the natural waistline. I'm personally not so keen on Kate's penchant for raised waistlines. Make the most of that lovely long, slender waist, girl :) Love the up-do, it's classy and shows off the earrings nicely. I would like to see the dress with the beige bow belt attached and feel it would have gone nicely with the taupe shoes and clutch, but then again, maybe less is more.
Ann
Wednesday 1st of August 2012
The Duchess looks as if she has put on some weight. She looks so much more beautiful. I hope she keeps it on.
alison
Wednesday 1st of August 2012
Absolutely beautiful. Lovely to see her hair up.
Tracey
Tuesday 31st of July 2012
Updo is polished and elegant, reminiscent of Jacqueline Kennedy (a political wife style icon if ever there was one)!
It may be due to the 60-ish look of this chignon, particularly the seemingly "poufy" part of it toward the back that others pointed out. Make-up seems softer, less harsh use of eyeliner, which is a nice change.
The issue for me with this ensemble, which I think is echoed by aspects of several other comments, is that there is a disconnect between the formal and less formal elements of it:
The evening bag, hairdo, and earrings look very formal, and like they belong together. The dress and the shoes are more casual, and look like they belong with each other. But, all 5 don't belong together as one outfit, I think.
A more casual bag would have fixed the problem, but this embellished Jimmy Choo is unquestionably formal, and creates the biggest conflict with the whole look. It belongs with the long formals and glittering evening shoes she normally wears it with.
I agree with everyone who is wondering why she doesn't wear the pale grey pumps she wore with this dress in the CA appearance last July, and (seemingly) matching pale grey clutch she carried at Order of the Garter 2011? Her mother also has a pale/dove grey clutch that she wore to the wedding, maybe could have borrowed that?
Khola
Tuesday 31st of July 2012
Oddly enough, I've never noticed Kate's wedding band (as seen in the pic above).