Peter Enrione Turquoise Wool Outfit and Rachel Trevor Morgan Hat

The Queen debuted this bright turquoise wool dress with matching coat on 25 December 2012, for the traditional Christmas Day appearance at St Mary Magdalene Church on the Sandringham Estate.
What's most striking of this coat, apart from the colour, is the geometric detail of the buttoning. The hat is by Rachel Trevor Morgan and made from the same wool material, with an upturned brim and flower trim.
For the Christmas Day appearance, the Queen completed the look with a black fur scarf and the flamboyant Diamond Jubilee brooch presented by the British Jewellers' Association:

 

The outfit was repeated almost a year later, on 8 November 2013, when the Queen and the Duke of Edinburgh officially opened the headquarters of SSAFA (Soldiers' and Sailors' Families Association) in London. Founded in 1885, the Soldiers' and Sailors' Families Association is a British charitable organisation providing assistance to former and serving members of British Armed Forces and their families or dependants.
No scarf was worn on this occasion, so we got a glimpse of the dress, which appears to be made of a brocade type material in a floral motif.
Queen Victoria's Pearl Pendant brooch was used:

On 28 May 2014, the Queen wore the dress on its own to hold audiences at Buckingham Palace. Below she is seen with His Excellency Mr Nestor Osorio Londono, Ambassador from the Republic of Colombia to the Court of St James's:

A few months later, on 17 October 2014, the dress was chosen once again, for investitures at Buckingham Palace; among those honoured was Maggie Smith, who was made a member of the Order of the Companion of Honour:

The complete outfit, this time accessorised with the Tudor Rose brooch, was worn again for a visit to the Jaguar Land Rover plant in Walsall, West Midlands, on 30 October 2014:

Less than a month later, on 25 November 2014, we got another look at the dress that goes with this coat, when the Queen wore it again for audiences at Buckingham Palace, accessorised with what looks like the Round Cambridge Emerald brooch with pendant. Below the Queen is shown with His Excellency Mohammed Abdalla Ali Eltom, the Ambassador of the Republic of the Sudan to the UK:

Almost a year passed before we got to see this outfit again - Her Majesty selected it for the official opening of the new School of Veterinary Medicine at the University of Surrey on 15 October 2015 (Daily Mail article here). The Pearl Trefoil brooch was used:

A few months later, on 4 February 2016, Her Majesty repeated this cheerful ensamble for a visit to the Norfolk Hospice, to open its new facilities at Tapping House near Sandringham (Daily Mail article here). She wore her Mappin & Webb crystal orchid brooch:

The Queen was presented with teddy bears for her great-grandchildren Prince George and Princess Charlotte during the visit:



On 18 October 2016, the Queen wore the dress to receive in audience at Buckingham Palace the Governor of South Australia, the Hon. Hieu Van Le, and his wife. She accessorized with the round Cambridge emerald brooch with pendant:

The Queen wore the outfit again on 14 February 2017, when she opened the new National Cyber Security Centre in London (Daily Mail article here). She wore the round Cambridge emerald brooch without pendant: