The Duke and Duchess of Cambridge, accompanied by Prince Harry, are in Arosa, Switzerland, this weekend to attend the wedding of a polo-playing friend of the princes.
Mark Tomlinson is marrying Laura Bechtolsheimer, a Team GB gold medal winner in the London 2012 dressage event.
She won team gold and individual bronze on her horse Alf at London 2012, and Old Etonian Mark proposed three weeks later.
The ceremony is due to take place on Saturday 2 March at a church in the remote town of Arosa in eastern Switzerland. The royals are among 250 invited guests.
Shortly after arriving in the country yesterday, the Duchess was spotted carrying a wooden sledge, while wrapped in a brown coat and wearing oversized sunglasses.
Princes William and Harry, both keen skiers, took to the slopes in the afternoon although the pregnant Duchess stayed at the hotel to rest.
The royals dined with fellow wedding guests at a mountain restaurant, where they feasted on raclette, the traditional Swiss cheese dish.
Laura Bechtolsheimer is the granddaughter of German billionaire and property magnate Karl Heinz-Kipp.
"Off to Switzerland now to get into wedding mode..eeek! #grown up!?" she tweeted on Tuesday. The couple became engaged in August last year.
William and Harry have played polo with Mark for many years and the Prince of Wales is a close friend of his parents, who own the exclusive Beaufort Polo Club near Highgrove.