Along with The King and Queen Camilla, Prince William and Princess Kate, who share a close bond with the Edinburghs, are said to be joining the festivities. The Princess of Wales and Duchess of Edinburgh are said to have a particularly strong relationship, with Kate viewing Sophie as a sort of "royal sister."

As a source told VF, the Duchess of Edinburgh, a new family favorite, "prefers to keep the attention on her causes and charities rather than on herself."

Congratulations are in order as Duchess Sophie gears up to celebrate her 60th birthday on Monday 20 January. In a slight deviation from tradition, the Royal Family has already marked the special day, taking to Instagram today to share a new photos showing the Duchess looking relaxed and happy ahead of the celebrations.

I love how she is not afraid to try new things and she makes beautiful choices,” designer Suzannah Crabb of royal favorite Suzannah London tells PEOPLE

Sophie, the Duchess of Edinburgh is turning 60 in style. The royal—who marked her milestone birthday on Monday, January 20—released a trio of stunning portraits to commemorate the special occasion over the weekend that seemingly included a subtle sartorial nod to her grand new title.