Britain's Prince William and Kate, Duchess of Cambridge and their newborn baby princess, pose for the media as they leave St. Mary's Hospital's exclusive Lindo Wing, London, Saturday, May 2, 2015.  Kate, the Duchess of Cambridge, gave birth to a baby girl on Saturday morning.
camera (Alastair Grant/AP Photo) Britain's Prince William and Kate, Duchess of Cambridge and their newborn baby princess, pose for the media as they leave St. Mary's Hospital's exclusive Lindo Wing, London, Saturday, May 2, 2015. Kate, the Duchess of Cambridge, gave birth to a baby girl on Saturday morning.

Now that Princess Charlotte's christening has been confirmed for early July, a new question awaits: Who will the Duke and Duchess of Cambridge appoint as their only daughter's godparents?

A royal godparent traditionally makes his or her first big appearance at the christening, and they’re expected to play a big role in a young royal’s life.

“There's a feeling that because of their role as members of the royal family that they need as many confidants as they can get apart from their parents,” said Robert Jobson, royal editor of the U.K.'s The Evening Standard.

So who is possibly on the shortlist?

Royal babies traditionally have about six godparents. William and Kate, like Princess Diana, are thought to want their newest child’s godparents to be a blend of traditional and more modern choices. That's how they chose godparents for their nearly 2-year-old son, Prince George.

Many people would like to see Pippa Middleton, Duchess Kate's younger sister, as well as Prince Harry, William’s younger brother, selected, but royal experts say that’s unlikely.

“Tradition for godparents is not to choose members of the family, certainly not the immediate family,” said Victoria Murphy, royal correspondent for The Daily Mirror and ABC News' royal contributor.

Zara Phillips Tindall, Olympic medalist and equestrian, the granddaughter of the Queen and daughter of Princess Anne, was selected to be Prince George's godmother. Zara and her brother, Peter, grew up spending time side-by-side with her cousins, Princes William and Harry.

Royal insiders say Peter Phillips, Princess Anne's oldest child and the Queen's first grandchild, is a favorite for a role as godfather to Princess Charlotte

Peter was so close to William and Harry during their childhood and teenage years that Peter was called to Balmoral immediately after the death of Princess Diana in 1997 to support Diana's sons, William and Harry.

Still, William’s step-siblings -- Duchess Camilla’s daughter, Laura Lopes, and her son, Tom Parker Bowles -- are possibilities. Another possibility is William's cousin Princess Eugenie, the daughter of Prince Andrew and Sarah Ferguson.

Kate and William, who first became sweethearts in college, could also pick from friends they met together.

“I think it is possible she might choose a good friend from university this time,” ABC News Royal Contributor Victoria Murphy said, referring to Duchess Kate.

The friends who are likely to make the cut include William’s longtime pal, Thomas van Straubenzee, who attended Ludgrove and Eton with William. Old Etonian Fergus Boyd and Olivia Bleasdale, who shared a house with William and Kate when they first fell in love at St. Andrews, are firm favorites also.

Captain Mark Dwyer, who has been a longtime mentor to William and Harry, and Tiggy Pettifer, who was the princes' beloved nanny, also could make the cut.

They pair could also pick one of their most trusted aides, such as Kate's chief of staff, Rebecca Deacon, or William’s chief of staff, Miguel Head.

Finally, don't count out Princess Diana's sisters, Lady Sarah McCorquodale and Cynthia Jane Fellowes, Baroness Fellowes.

The Duke and Duchess have honored William's late mother every step of the way. William, of course, gave Kate his mother's engagement ring and, in a poignant tribute to Diana, they recognized her in Princess Charlotte Elizabeth Diana's name.

Princess Charlotte's July 5 christening will take place at St. Mary Magdalene, the same church where Princess Diana was baptized in 1961. William and Kate have indicated their children will be reminded of their grandmother's place in history. What better way to honor Diana than to let select one of her sisters as Princess Charlotte's godmother.

Whomever William and Kate pick, one thing is certain. The godparents will need to be prepared.

“When they pick people to be godparents, they're putting them into the spotlight and some of their friends really don’t want that be in the spotlight, so it will definitely be someone who is kind of willing to take that on,” Murphy said.