Prince Harry revealed to The Telegraph that he is worried about his brother Prince William's children, Prince Charlotte and Prince Louis, and that one of them will end up as the "spare" in the next generation of the royal family, the "heir" to Prince George.

The role of "spare" has so profoundly defined Harry's life that he gave the nickname the title of his memoir, which was released this week to record sales.

"I'm well aware that, in my family, if it's not us, it's going to be someone else," Harry said, referring to himself. [I've talked to William once or twice, and he's made it clear that his children are not my responsibility, but at least one of his three children will be like me. And that hurts me and worries me."

For those new to the royal lexicon, "heir and reserve" refers to the eldest son, or heir to the throne, and any other children born after him, somewhat wildly called reserve, in case something should happen to the future monarch.

In his memoirs, Harry wrote to his wife, Princess Diana, on the day his father, King Charles, was born, "It's wonderful! Now I have an heir and a spare.

While Harry was the only "spare" to his brother William's "heir," technically both Charlotte and Louis could be referred to by that title; prior to the 2013 Succession to the Throne Act, even though Charlotte is older than her brother Louis, he is male Louis in the line of succession, but thanks to the 2013 law, Charlotte remains third in the line of succession to the throne, directly behind George and ahead of Louis, regardless of gender, even though she is a woman.