Britain's Catherine, Duchess of Cambridge is shown around the Tashichho Dzong temple by Queen Jetsun Pema Wangchuck in Thimphu, Bhutan, April 14, 2016. [Photo/Agencies]

The 25-year-old queen, born a commoner, as Kate was, is viewed as a style icon across much of Asia. Both couples have started families, with Jetsun Pema giving birth to her first son, the crown prince, this February.

"The prince and princess of England have never visited Bhutan, so, I think it is a great moment for Bhutan," said Tsering Pem, a resident of the capital, Thimphu, where the 16th-century seat of government was given a fresh coat of paint before the visit.

"Two of the best royal couples in the world are meeting, so I think it is pretty exciting," she said.

During their two-day stay the British royals, who have been touring India, will trek to the Tiger's Nest, an ancient Buddhist monastery perched 3,000 metres (10,000 feet) up a mountain.

William's father, Prince Charles, failed to complete the steep ascent to the Tiger's Nest during a visit in 1998, opting instead to paint a watercolor of the scene.

Their week-long tour ends back in India next Saturday at the Taj Mahal, revisiting the scene of a solo - and much photographed - visit in 1992 by the late Princess Diana, to the monument to love.