The Duchess wore an elegant one-shouldered gown for tonight’s BAFTA (British Academy of Film and Television Arts) Awards ceremony.
The event is held at Royal Albert Hall and is much like the Oscars/Academy Awards in the US.
Prince William is President of the Academy; a position he has held since 2010. 
The couple being seated.
The Duke and Duchess of Cambridge take their seats for tonight’s @BAFTA Awards Ceremony #EEBAFTA pic.twitter.com/76hNXDZIxp
— Kensington Palace (@KensingtonRoyal) February 10, 2019
Another view.
Just before the program got underway.
This 2-minute video covers the arrival and the couple being seated. About :30 seconds into the video you can see how Kate’s dress moves in the wind. If you want to look at it after reading the post I’ll have a link at the bottom of the page.
After the event concluded William and Kate met award winners, nominees, and presenters.
The Duchess of Cambridge congratulates Rachel Weisz, winner of the @BAFTA Award for Best Supporting Actress in The Favourite. #EEBAFTAs pic.twitter.com/0na1yro4a5
— Kensington Palace (@KensingtonRoyal) February 10, 2019
The Duchess with Spike Lee.
The Duchess of Cambridge congratulates Spike Lee, Director of BlacKkKlansman, which won the @BAFTA Award for Best Adapted Screenplay. #EEBAFTAs pic.twitter.com/IDggiywOmF
— Kensington Palace (@KensingtonRoyal) February 10, 2019
Now for our look at what Kate wore, starting with her Alexander McQueen evening gown.
A closer view. 
The one-shouldered design features a draped, fitted bodice with a full, flowing skirt. 
It is much like these two Alexander McQueen designs. The material seems similar to the crinkled silk chiffon used on the design seen lower right.
A tip of the tiara to Laura (aka Japanese Ginger); last night when predicting the style gown she’d like to see Kate wearing this evening she selected the lilac dress seen above!
Upon seeing Kate tonight many of us shared the same thought: it looks a lot like the gown worn to the Prince Charles 70th birthday party. 
Here is a side by side comparison. 
According to Hello! the Duchess has the gown in two colors.
The dress featured a floral motif on the shoulder and ruffled detailing. Kate actually wore the dress to Prince Charles’ 70th birthday dinner last November, but in hot pink.
The skirt of tonight’s gown was somewhat reminiscent of the lavender Alexander McQueen worn to the 2011 BAFTA gala in Los Angeles.
Kate was in a pair of Jimmy Choo heels, the label’s Romy 100 Delivered with Chocolates style ($725). The design is called the Dégradé Glittered Suede Pump at Net-a-Porter. 
It is the classic Choo Romy, with its point toe and 4″ stiletto heel, adorned in silver and blue dégradé glitter. Many thanks to Laura for IDing the pumps.
Kate carried a white clutch this evening that looks like it could be a bespoke piece from Alexander McQueen. UPDATE NOV 19 2019: I have inserted a new photo montage below that includes the Alexander McQueen Butterfly Box Clutch. It is no longer available in Kate’s finish and color, but you can see it in a pink style at Saks. 
A closer view of Kate’s updo.
It allowed us to see the earrings she wore tonight.
The Duchess wore a new pair of earrings tonight that belonged to Diana, Princess of Wales. The Telegraph does a good job describing them: “The earrings feature a double curve of various cuts of diamonds, with a cluster of marquise-cut stones in the centre.” 
The late Princess wore them with some frequency.
More about the earrings from this Telegraph story:
Princess Diana wore the earrings with sizeable, silver-toned South Sea pearl drops on several black-tie occasions.
They are versatile too, due to the removable pearl drop. Diana wore the earrings without the drop at her final public appearance, to a performance of Swan Lake at the Royal Albert Hall in June 1997, just weeks before she died.
Here you see Diana as she arrived at the Swan Lake performance. In the lower right I added a closeup of an earring.
Nor are they the Collingwood pearls. Below left, Kate’s earrings tonight and on the right, the Collingwood pearls worn on another occasion; you can see the difference between the caps.
The Duchess also wore the Queen’s Diamond Quatrefoil Bracelet.
We first saw her wear it at a 2017 gala for the Anna Freud Centre. Below it is shown (left to right) as worn this evening, at the Freud Centre gala and on HM’s wrist at the 2010 State Opening of Parliament.
This info comes via From Her Majesty’s Jewel Vault: “The wide diamond bracelet features multiple diamond quatrefoil motifs, the four-lobed design popular in architecture, art, heraldry, and elsewhere. Each quatrefoil outline is filled with five individual diamonds.”
This was an outstanding look for Kate, one that might belong in our Iconic Looks category. Below, a look at the Duchess in tonight’s Alexander McQueen design, the Jenny Packham worn to the 2018 awards and the off the Shoulder Alexander McQueen dress seen at the 2017 BAFTAs. 
We’ll leave you with this black and white image of the Duchess.
VIDEO:
As noted above, this 2-minute video covers the arrival and initial seating.
This is about 5 minutes showing the Duke and Duchess meeting many of the award winners after the program concluded.
LINKAGE:
- The Mirror’s coverage is here; The Daily Mail’s story is here; The Telegraph’s story about the earrings is here
- Town and Country’s gallery is here; Grazia UK’s piece is here; Hello’s coverage is here; the Fug Girls post is here; a PopSugar gallery is here
saree
Wednesday 9th of June 2021
I can't forgot this dress. As she got the princess look in this outfit.
shannon maxwell
Wednesday 27th of March 2019
She looks like a regal film star like grace kelly and audrey hepburn absolutely stunning.
Amy
Sunday 17th of February 2019
Hands down one of my all-time fave DoC looks! Stunning, breathtaking, and so regal!
Amelie
Friday 15th of February 2019
This is one of the prettiest gowns Kate has worn in awhile. It ranks up there with the teal Jenny Packham and lavender Alexander McQueen. White can easily look too bridal and while you could wear this theoretically as as wedding dress, it would be a very untraditional wedding dress with the one shoulder and floral embellishment at the shoulder. It just fits her so well and the minimal jewelry is great. The one thing I don't like is her updo. She favors chunky big updos and while I'm glad she wore her hair up, I often find I'm not a fan of her updos.
Larissa
Friday 15th of February 2019
There is really nothing wrong with this outfit, so I can't quite put my finger on why it doesn't excite me as much as many of Kate's other evening looks (albeit the evening looks I've liked most have been almost entirely pre-2018, which I found to be a bit of an underwhelming evening gown year). I think it's all just my personal taste. I've never been a big fan of one-shoulder looks – especially in white, I think they have a tendency to look toga-esque very quickly. I really love the fabric on this dress, and it's nice to see Kate continues to switch up colours in her eveningwear. I also appreciate the flower embellishment which does help to stay away from toga territory. But it just isn't a favourite look of mine because it's not a style I'm drawn to.
I'm not sure what it is about the updo that bothers me, it's certainly less helmet-y than the 2017 BAFTAs and less stiff than the low chignons we often see. Perhaps it looks better in person when one can appreciate the details. But particularly in the side view, with that piece of hair that covers the bun standing out, I'm not a fan. The earrings are certainly interesting and I like to see Diana's pieces make appearances; however I'm not really fond of the two half circles, they look a bit too big for an earlobe.
All that being said, Kate does look radiant, there is no denying that. Love the shoes, love the bracelet, and love that the Duchess is not afraid to show off her fit shoulders and arms every once in a while!