The Duke and Duchess of Cambridge hardly fall within the definition of normal parents-to-be, since their first-born will be third in line to the throne.

But Prince William and Kate are apparently wrestling with one common conundrum facing couples awaiting their first child: Just what to name the baby?

"We have a short list for both

[a boy and girl], but it's very difficult," Kate was widely reported as saying the other day.

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Kate, the Duchess of Cambridge, visits Naomi House Children's Hospice near Winchester, England, on April 29, 2013, the second anniversary of her marriage to Prince William. (Max Mumby/Indigo/Getty Images)

"My friends keep texting me names."

British bookmakers have lists of possible names, too. Ladbrokes' betting pool is even offering odds on monikers as diverse as Adele (200 to 1, and likely inspired by the powerhouse U.K. singer) or Elvis (500 to 1, another interesting musical nod).

But those who temper their speculation with historical insight point to other more likely influences over the name of the baby expected in mid-July.

"Royal baby names tend to be chosen on the basis of tradition, after previous monarchs or royal godparents," says Carolyn Harris, a Toronto-based royal historian and blogger.

So a name like Elizabeth, Anne or Mary might find favour if this child is a girl. Charles, George, Edward or James might be possibilities if it's a boy.

Rumours and speculation about the baby's sex have flown fast and furious, but nothing official has been confirmed. On Sunday, British tabloids were reporting that William's brother Prince Harry was telling friends the baby is a boy. Reports a few days earlier also hinted a boy is in the cards when Kate apparently bought a very fancy pale-blue baby buggy. Then again, other reports suggested Kate almost let it slip she's expecting a girl.

Bets on Alexandra

If the oddsmakers are to be believed, Alexandra was the prime choice for a girl — one bookie even temporarily suspended betting on that possibility.

Ladbrokes was still putting Alexandra at the top of its list last week, at 2-1 odds, and it's a name that Harris says holds a lot of royal history.

"There were three kings of Scotland in the Middle Ages named Alexander. So at a time when Scotland is discussing devolution, naming a royal baby Alexandra would reinforce the Crown’s connections to Scotland."

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This March 3, 1927, photo shows nearly-one-year-old Princess Elizabeth - full name Elizabeth Alexandra Mary - who became Queen Elizabeth in 1952. (The Royal Collection, Marcus Adams/Associated Press)

Then there's the fact that Queen Victoria's first name was actually Alexandrina, in a nod to her godfather, Alexander the First of Russia.

King Edward VII, who reigned from 1901 to 1910 and whose popularity wavered over time given that he dabbled with both gambling and mistresses, had a very well-regarded wife named Alexandra. And the current Queen, whose second name is Alexandra, also has a cousin with that name who is a hardworking member of the Royal Family.

But what if William and Kate, like so many parents, want to do something a bit different with the name of their first-born?

As much as they might want to, observers consider it unlikely they will stray too far from the royal ways, particularly for the child's first name.

"I think simply that there’s a kind of institutional stuffiness that we call tradition that will be forced upon them," says Ninian Mellamphy, a longtime royal watcher and professor emeritus at Western University in London, Ont.

Beatrice and Eugenie

Within that tradition, though, there may be ways to bring in a name that hasn't had a high profile on the royal roster.

"Drawing on royal tradition doesn’t always mean a well-known royal name," says Harris, pointing to Beatrice and Eugenie, the 20-something daughters of Prince Andrew and Sarah Ferguson.

"Princess Beatrice is named after Queen Victoria's youngest daughter Beatrice and Princess Eugenie is named for Napolean the Third's wife. These were names with royal antecedents, but more obscure ones."

Of course, royal names of children high in the succession to the throne tend to be long ones — although rarely as long as that of Edward VIII, who was officially Edward Albert Christian George Andrew Patrick David, the last four names being the patron saints of England, Scotland, Ireland and Wales.

While few other royal names have rivalled that for length, second or third names have given royal parents the opportunity to acknowledge the other side of the family or bring in other historical influences.

Topping the charts

If William and Kate were following naming trends in the United Kingdom, they'd look no further than William's younger brother Harry for inspiration. Harry was the top choice for a boy's name last year, according to website babycentre.co.uk.The top girl's name was Amelia.

In Canada, William would find some interesting inspiration for a boy's name closer to his own heart. According to the Today's Parent website, the top baby names last year were William and Maya/Mia/Mya.

Arthur — of Arthurian legend — turns up frequently, and Philip (for the Queen's husband, the Duke of Edinburgh) registers in the names of both William and his father, Charles.

This time around, Harris wouldn't be surprised if Elizabeth or Diana (for William's mother) were among the names for a girl, and Philip or Charles or Michael (for Kate's father) show up if it's a boy.

But Mellamphy sees reason to be cautious about Diana, particularly as a first name.

"I think in royal history that Diana will remain unique now because there was all that praise, but all that blame as well. I think if you were called Diana, you'd in some way inherit some nuances of her foolishness."

Even choosing Diana as a middle name seems questionable in Mellamphy's mind.

"I have a funny feeling she's too well remembered and there’s too much ambiguity about our memory of her."

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Prince William - full name William Arthur Philip Louis - amuses his parents Prince Charles and Diana, Princess of Wales, during a photo session at Kensington Palace in London in December 1982. (Associated Press)

Still, William has shown stubborness and determination in the past, and clearly values deeply the memory of his mother (he gave Kate her iconic sapphire engagement ring). So seeing Diana in his daughter's name would not be a total surprise.

Whatever name the child ends up with wouldn't necessarily have to be the name he or she would use on the throne.

The Queen’s father, George VI, opted for his fourth name, and continuity with his father (George V), rather than use his first name, Albert.

Victoria went with her second name when she became queen in 1837. At that time, Harris says, the name Victoria would have been considered foreign and unusual for a queen.

Now, though, it's a name that seems very regal, and which Ladbrokes puts at 6-1 odds for the next royal baby.

What about Matilda?

One name not on the Ladbrokes' list, but which Harris thinks would be intriguing, is Matilda.

"It's interesting that considering succession reform, and that if the baby is a girl, she will one day be queen. I think it would be interesting if Matilda was chosen just because she was the first woman to make a claim for the English throne in 1141," says Harris.

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Prince William and Kate, Duchess of Cambridge, leave the King Edward VII hospital in central London on Dec. 6, 2012, after she was treated for a severe form of morning sickness in the early stages of her pregnancy. (Alastair Grant/Associated Press)

"I don't think it's a likely choice but it's an interesting one historically."

Mellamphy also looks deep into history and sees names that are unlikely to figure in the considerations of Kate and William.

"They couldn't go back to the beginning of English kings with Aethelstan and names like that, you know, Alfred — not to mention Ethelred the Unready."

While Harris sees the strong historical precedent facing William and Kate, she still expects they will be able to exert some personal influence over the name.

"The Duke and Duchess of Cambridge have always approached royal protocol their own way," says Harris.

"They were together for many years before becoming engaged. They were able to have a certain degree of private life early in their marriage by living in Anglesey in Wales, and so clearly the baby's name will reflect their own wishes as well as royal traditions."