Jenny Packham yellow dress

During the Canada tour of 2011 on a stop at Calgary, the Duchess wore this bright yellow Jenny Packham dress.  Its not quite a shirt dress but the bodice is definitely styled like one, with a button front placket, collar, and short sleeves, paired with a flowy A-line silhouette skirt.

Via DM.

Let me just say the dress is fine, but it isn't a very exciting or interesting dress and paired with the nude shoes the outfit itself is a bit boring.  The waistline here has a bit of awkward placing because it is a bit high, making the bodice fit short on Kate's long torso.  I think the combination of the high waistline paired with an above the knee hemline isn't very good on Kate since it makes her dresses look like the fit is too short for her.
But I like the good balance and proportion of Kate strong shoulder with a fuller skirt.  The fuller sleeves do help mask and soften that strong shoulder while the full skirt helps give a feminine shape.  I like when she mixes it up with fuller silhouettes since she does seem to favor the sheaths.
The only downside is that it was not as appropriate for the windy condition and as you can see in the photo she struggled to keep the hem wrangled  Maybe a slip would have helped or maybe dress weights, but for future reference this would be one occasion where her more structured sheath silhouettes would be better suited.

I didn't find a ready made repliKate but I did come across this interesting pattern set for any of you DIY-ers out there.  It features a pattern for a dress almost identical to Kate's.  It has the same button down bodice with collar and sleeves paired with a flowy fuller skirt.  It even appears to have similar dart placing at the bodice.
Its a bit of a coincidence that the yellow dress is featured so prominently in the envelope, so clearly it is meant to be an inspiration of Kate's original.  The other dress in the set is a long sleeved wrap style.

Simplicity brand pattern set # 1880.

Pleated Day Dresses

Two of the Duchess' Jubilee-event dresses were big hits and surprisingly they were very similar.

On May 29, 2012 - below left - at a Buckingham Palace garden party, Kate wore a pale pink Emilia Wickstead dress with a square neckline, long sleeves, and pleated skirt.  Then on June 2 - below right - at the Jubilee flotilla parade she wore a tomato red Alexander McQueen dress with long sleeves, pleated skirt with peplum, with (appropriately enough) a bateau stye neckline.

Two different custom dresses from two different designers yet the common denominators were the pleated skirt, high neckline and natural waisted bodice, A-line silhouette and long sleeves.  Actually looking at them side by side with their matching similarly cocked hats and Kate's standard issue nude pumps, they don't look too dissimilar do they?

Both via: Instyle.

I actually enjoy both these looks on Kate since I feel the A-line really evens out her long, strong shoulder line and gives her slim-hipped figure some shape.  Dressing for your figure includes making sure your proportions are evened out and the unflattering parts are minimized, and these two dresses to a great job of visually proportioning Kate's troublesome wide shoulders and narrow hips.

The square neckline on the left does a great job of shortening that shoulder line, though it would look just a bit more proportioned if the skirt was a bit fuller and filled in those hips.  Meanwhile the boat neckline on the right almost risks once again elongating those already long shoulders, but is saved and fully balanced by the wider A-line silhouette and the peplum, which carve out a really great shape and mask those slim hips.  Its probably one of my favorite Kate looks of all time mostly because it got her proportions just right.

Via: L - InStyleUK; R -  ExpressUK.

The first repliKate I found was in Do-It-Yourself sewing pattern form.  I'm not sure how advanced the pattern is but it would be a fun project for the home seamstress.
I think this dress captures the essence of both dresses first and foremost because of the strong pleated line.  Even though this pleat detail is only a small asymmetrically placed panel, it is a full A-line silhouette.  The squared v-neckline also recalls the neckline on Kate's pale pink dress.  This dress comes with 3 hem length options (above knee, below knee, and full length) as well as the 2 sleeve options shown below.  I'm sure a more experienced home seamstress could full craft some full-length sleeves for a more spot-on replica.

McCalls Pattern no. M6433, dress version B.

McCalls Pattern no. M6433, dress version A.

Another repliKate I found was this red sleeveless A-line dress with pleated skirt by Calvin Klein.  It follows the basic formula of the original, a clean bodice with pleated skirt and high placed neckline, though of course it lacks certain details like the sculpted peplum and long sleeves.  Its a nice alternative though and a great basic.

Calvin Klein via Macy's - red pleated A-line dress.