Katie Couric interviews Prince William for the ABC network special, "The Jubilee Queen With Katie Couric." (Credit: Mark Large)

One year after their marriage, Prince William said that he and wife, Catherine Middleton, the Duchess of Cambridge, are eager to have children. What he didn't say was exactly when the world could expect to meet the next British royal heir.

"I'm just very keen to have a family and both Catherine and I, you know, are looking forward to having a family in the future," the Duke of Cambridge, 29, said in an interview with ABC News' Katie Couric. Asked by Couric if there was anything else he wanted to share, he answered with a laugh, "You won't get anything out of me. Tight lipped."

To mark the Queen's Diamond Jubilee, celebrating her 60 years on the throne, Couric conducted several rare interviews with members of the royal family, including TRH Prince Harry, The Duke of Cambridge Prince William and The Duke of York Prince Andrew, which aired in an ABC News special called "The Jubilee Queen With Katie Couric."

Speculation about whether Kate Middleton is pregnant has been swirling for months. Meanwhile, whenever the royal couple does have children, it appears likely their first-born will be in line for the throne regardless of gender. Last year, the heads of 16 Commonwealth countries agreed to a change in the rules of succession so that first-born children of either gender - rather than only first-born males - can take the throne. (Queen Elizabeth II was only eligible to be sovereign because her father had no male children.) The British Parliament must still amend existing law to make the succession change official.

"Put simply, if the Duke and Duchess of Cambridge were to have a little girl, that girl would one day be our queen," British Prime Minister David Cameron told reporters last year.

Prince William said he thought it was strange that his family planning was the subject of headlines, but he tries not to let it bother him.

What does bother the prince, however, is the decision he has to make by the end of this year: whether to take another tour of duty with the Royal Air Force - where he is a flight lieutenant - or assume royal duties full-time.

"I'm still trying to decide," he said. "It's a really difficult one because I really enjoy my time in the Air Force. And I'd love to continue it. But the pressures of my other life are building. And fighting them off or balancing the two of them has proven quite difficult."

Like his older brother, Prince Harry has followed his family's long-standing tradition of military service. He is a captain in the British Army Air Corps and famously had a tour in Afghanistan in 2007 and 2008.

In Afghanistan, he said, he learned what it meant to fight for queen and country.

"Once you're in the military, she means a lot more to you than just a grandmother. She is the queen. And then you suddenly, it's like start realizing, you know, wow, this is quite a big deal. And then you get goose bumps and then the rest of it," he said.

Prince Harry is still figuring out his personal life, he said. The 27-year-old prince shared with Couric his own desire for a family.

"I've longed for kids since I was very, very young. And so … I'm waiting to find the right person, someone who's willing to take on the job," he said.