SIMON DAWSON/Invision/AP 1 / 9
SIMON DAWSON/Invision/AP 1 / 9

With Duchess Kate and Prince William's Dec. 3 announcement that they're expecting a royal heir, no one is more excited about the news than William's father, Prince Charles.

"It's a very nice thought to become a grandfather in my old age, if I can say so," Charles, 64, told reporters at the launch of the 2012 Antarctic Winter Crossing Expedition in London on Thursday. "I'm thrilled. Marvelous."

PHOTOS: Royal pregnancies

The couple's son or daughter will be the first grandchild for Charles, also the father of Prince Harry, 28, with the late Princess Diana.

Hospitalized with complications from extreme morning sickness Dec. 3, the pregnant royal was escorted home Thursday with William by her side. Upon her release, Kate, 30, assured reporters she's feeling "much better."

VIDEO: William and Kate dish on starting their family

"Trying for a baby has been their priority, a royal confidant told Us shortly before the couple revealed their happy news. "They're both excited to be focusing on a new chapter in their lives."

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