The couple, who are wrapping up their week-long tour of Bhutan and India, told reporters at the end of their 10,000-foot hike in Bhutan that they couldn't wait to see their children again. And they hope to bring them along one day when "they're a little bit more mobile," Kate said.
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But they have been calling home regularly. Asked by PEOPLE if they had been able to speak to the children, William said, "Yes we have. Many times."
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It's believed they are being cared for by nanny Maria Turrion Borrallo and grandmother Carole Middleton.
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"Beautiful scenery as you saw," William told reporters "With the mountains like this and the temples at the top it was just stunning to walk up there and see all the scenery and to listen to some of the history and religion of the country.
"It's really important when you come on a trip like this to see some of that."
He had previously said that the hike was 'easy' when he reached the half-way point earlier in the day. Was that too ambitious? "I may have slightly spoken too soon. It was a little bit cheeky on the second part definitely."
Kate was asked how she found it. "It was an amazing experience. I feel very lucky and fortunate to see such beautiful scenery. As William said, learn about the country."
William was following in the footsteps of his father Prince Charles who had made a similar hike in 1998 – although he didn't get to complete the entire trek.
"My father didn't make it to be top," William said. "So that's something I'll be reminding him of when I see him."
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"It will be lovely if the children could come as well, definitely," he added.
Kate said, "We did actually see one family up there with a small child on their front. It was very brave of them."
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At the end of their trek the couple browsed a little market of stalls selling tourist gifts, from small Buddha models to locally-made necklaces and fridge magnets.
William picked up a bronze model of a tiger for 200 rupees ($3) and Kate snapped up a bargain pair of earrings for 500 rupees ($7).