Prince William is "making a stand for the future".

French magazine Closer published topless pictures of his wife Catherine Middleton while the pair were enjoying a holiday in Provence last week.

Long-lens shots of the brunette beauty were taken beside a private swimming pool.

The British royal family is incensed and it has been confirmed that a legal case has been filed against parties involved with the dissemination of the images.

Apparently Prince William was adamant about suing.

"By setting a precedent and suing Closer, Prince William is making a stand for the future," a source revealed to Radar Online.

"He told Kate that enough was enough, especially after what happened recently with Harry, and that he had to protect his wife and any kids they have in the future.

"He grew up in the media glare with his mom, Diana, and is well aware that he has to do something to ensure the Duchess of Cambridge's security and right to privacy."

Catherine reportedly didn't think it was such a big deal.

Prince William stands firm on his decision to go to court.

"But they're in two camps over this. Kate didn't want William to go nuts over the topless photos. She said she didn't mind turning a blind eye to them because they will soon be forgotten about," the source explained.

"However, William wants to go after Closer and put an end to press invasion once and for all."