White Outfit with Pewter Pixel Detail and Contrast Black Piping

The Queen debuted this look on 5 June 2014, during her visit to France to commemorate the 70th anniversary of the D-Day landings.
We first got a peek at the dress at St Pancras railway station in London, where the Queen marked the 20th anniversary of the opening of the Eurotunnel. The dress was worn underneath a white coat with navy bow trimming:

Upon arrival in Paris, the Queen emerged in a new short jacket and hat. The dress is minutely embroidered with pewter-coloured sequins that form a sort of pixelated motif, while the jacket is white silk/wool crepe trimmed with a large band of the same sequinned silk and contrasting black piping. The same trimmings are empoyed on the Angela Kelly white straw hat (Daily Mail article here). The Queen had swapped brooches as well, selecting the Botswana Sorghum brooch in favour of the sapphire and diamond grapes she had worn on departure:

 

The Queen repeated the outfit, minus the hat, on 4 July 2016, when hosting a reception at the Palace of Holyroodhouse in Edinburgh to recognize public service in Scotland (Daily Mail article here). This time she wore no brooch:

 

 

Aqua Printed Silk Dress and Jacket Combo, Quill-Trimmed Hat

This is a very versatile outift: a silk dress and jacket combo made from a fabric with a delicate, naturalistic floral print in pretty shades of aqua, blue and green and a baby blue bouclé coat and quill trimmed straw hat.

The dress, coat and hat combo was worn to a garden party at the Palace of Holyroodhouse in Edinburgh on 28 July 2005, together with the City of London Lily brooch:

The Queen wore this outfit again, in its dress and silk jacket combination, for a children's garden party at Buckingham Palace on 25 June 2006, part of her 80th birthday celebrations, paired with her Pearl Triangle brooch. During the event, the Queen and the Duke of Edinburgh met several well-loved children's books characters, including Postman Pat, Thomas the Tank Engine and Alice in Wonderland's White Rabbit (Daily Telegraph article here):

On 25 June 2008, the Queen was seen wearing again the dress when she received Nelson Mandela and his wife at Buckingham Palace. I'd say she was wearing the Pearl Trefoil brooch, although it's difficult to tell for sure:

The Queen wore the dress again on 4 May 2011, for audiences at Buckingham Palace (below, with the Ambassador of the Slovak Republic Miroslav Wlachovsky). She accessorized with her Boucheron aquamarine and diamond clips:

Coral Coat with Braid Trim and Coral Straw Hat by Angela Kelly

For Day 4 of the Royal Ascot races, on 17 June 2016, the Queen debuted a new coral ensamble, made up of a coral silk crepe coat with patch pockets, coral silk dress with white floral print and coral straw Angela Kelly hat trimmed with a bunch of feathers in shades of pink and coral. The coat is trimmed at the cuffs and pockets with braids made from the same fabric as the dress, which is also used to cover the buttons (Daily Mail article here). For the Ascot appearance, the Queen selected the Centenary Rose brooch to complete her outfit:

 

 

Pink Mottled Silk Suit

Unfortunately, I lack reliable information on this lightweight mottled silk suit, floral print on fuchsia pink background. The only picture I was able to locate of the complete outfit is the one shown below of the Queen boarding a plane, unfortunately I don't know when or where it was taken. The style of hat and the use of cream leather accessories, which is very rare these days, make me guess we're looking at a late 1990/early 2000s photo:

On 1 July 1997, Canada Day, the Queen wore the suit at Aberdeen Pavilion in Ottawa, during a royal tour of Canada. The airplane photo and this one were taken at different times, as you can tell the hat is a different style:

Anyway, the Queen chose to wear the dress again on 21 June 2016, when she was photographed sending her second ever tweet (you can find it here) to thank her followers for the well wishes on her 90th birthday, from the official Twitter account of the Royal Family (Daily Mail article here). She wore no brooch:

Pea Green Outfit with Camellia-Trimmed Angela Kelly Hat

The Queen debuted this bright pea green crepe coat with self-covered buttons and classic lapels, delicate floral print silk dress with pleating detail at the neck and Angela Kelly hat in green sinamay, with the crown covered in the same fabric as the coat and an oversized white camellia bloom on a visit to the Giant's Causeway in County Antrim, Northern Ireland, on 28 June 2016 (Daily Mail article here). She finished off the look with her diamond Art Deco brooch:

The Queen repeated the outfit on 1 November 2016, when she welcomed the President of Colombia, Juan Manuel Santos, and his wife at Horse Guards Parade, at the start of their 3-day visit to the UK (Daily Mail article here). The Queen appeared to be wearing a top and skirt underneath her coat, instead of the original silk floral print dress, and wore her ruby, diamond and gold floral brooch:

The Queen repeated the coat, this time with a different green dress underneath and a cheerful seaside-themed silk scarf, for her return journey from Sandringham to London on 7 February 2017, at the end of her annual winter stay in Norfolk (Daily Mail article here). She wore the Pearl Trefoil brooch:

The green dress that could be seen peeking out of the coat at King's Lynn in February was repeated on 8 March 2017 for audiences at Buckingham Palace. This time the Queen, shown below with Erlan Idrissov, Kazakhstan's Ambassador to the United Kingdom, wore the round Cambridge emerald brooch with pendant:

Pale Pink Angela Kelly Outfit With Berry-Trimmed Hat

For Day 2 of the Royal Ascot raceson 15 June 2016, the Queen debuted a new pale pink outfit by Angela Kelly, made up of a collarless coat with white frayed trim, a silk dress with a subdued black and white floral print on a pink background and a hat in pale pink straw trimmed with a spray of berries and a curling white straw ribbon (Daily Mail article here).
We also saw (gasp!) a new brooch: according to the Queen's Jewel Vault, it is a 1930s piece by Cartier, in the shape of a diamond-encrusted rose. I suspect this will be the first of quite a few new brooches that will make their appearance in the year of the Queen's 90th birthday:

#NeonAt90

The Queen's choice of a bold neon green outfit for her official 90th birthday celebrations and Trooping the Colour on 11 June 2016 certainly sparked comments and prompted the hashtags #NeonAt90 and #HighVisHighness to sweep social media.

A creation by Stewart Parvin, with a matching hat by Rachel Trevor Morgan with bright pink hydrangea trim, the outfit made the Queen immediately visible among the sea of red of the Trooping the Colour parade (Daily Mail article here, Daily Telegraph article here; for a funny take on the Queen's neon look see here; for a short video of the Queen 'telling off' Prince William on the balcony, see here). There is a somewhat more subdued flower print dress on cream background worn underneath. The Guards badge was worn as usual as a brooch: