Prince George has a special and adorable nickname for his grandfather, Prince Charles.

According to Abbie Llewelyn, a journalist for Express, Prince William and Kate Middleton's eldest son calls the Prince of Wales "Grandpa Wales" when they are together. The nickname is similar to the way Queen Elizabeth II calls her own grandfather when she was still a child - "Grandpa England."

Prince Charles and Prince George's special relationship goes beyond their sweet nicknames. In fact, the Duke of Cornwall refurbished Prince William's old treehouse so Prince George could play in it. He also named a group of trees in his Scottish estate after the third-in-line to the throne by calling it "George's wood."

"I hope it will be quite amusing for George, as they grow up, and he grows up," Prince Charles said.

Prince Charles will be celebrating his 70th birthday this month. Ahead of the celebration, the heir to the throne was asked if he felt optimistic about the world.

"I would be if we would just stop [explicit] about with the planet. I just worry about the sort of world my grandchildren are going to live in," Prince Charles said.

The Prince of Wales is an active advocate of the environment. At the age of 21, he made his first speech on how evil plastics are. But, he's still not sure if his efforts would make a difference.

"I don't know if it's made any difference," Prince Charles added with a sigh. "But I had to say something."

"I won’t be around to see the results of those," the royal said while pointing to an avenue of new limes he calls the Duchess of Rothesay's Walk.

In related news, Prince Charles reportedly does not approve Prince Andrew and Sarah Ferguson's romance. In fact, their relationship riles him.

"[Andrew] has been a liability to the Royal Family," Katie Nicholl said on Netflix's documentary "The Royal House of Windsor." "His relationship with [Sarah Ferguson] is one of the things, I’m told, that really riles Charles. It all contributes together into something that is just not very palatable."