London (CNN) -- Way back in the mists of time, when schoolkids were expected to learn seemingly endless lists of facts off by heart, they chanted a poem to remember the names of England's kings and queens.
"Willie, Willie, Harry, Ste," it began. "Harry, Dick, John, Harry three / One, two, three Neds, Richard two / Harrys four, five, six, then who?" It then ended with the most recent monarchs: "Edward seven, George and Ted / George the sixth, now Liz instead."
Of course, it's not done that way any more, but if it were, which name would make it into the next verse? We know that "Charles" and "William" will follow "Liz," but which name will follow theirs?
Long before it was announced that William and Catherine had had a baby boy, speculation about what they'll call the newest addition to the royal family reached fever pitch. Would they pick a name that has already featured in that schoolroom poem?
"William and Kate are very much a couple of the 21st century but I think they will stick to traditional names, in keeping with the past," Kate's biographer Claudia Joseph told CNN.
Whatever the pair pick as the all-important first name, there will be plenty of room to fit in nods to other members of the family too.
"Royals have quite a lot of names," said Williams. "Charles is actually Charles Philip Arthur George, and the Queen is Elizabeth Alexandra Mary. Her father, Bertie, had five names."
Writing for CNN, royal author Andrew Roberts agreed: "Although we can't know what the child's name will be, we can be sure that he or she will have a lot of them: Some heirs to the throne [have] had as many as seven or eight."
But now we know it's a boy, Williams said the couple's choice was simpler in theory, since there are fewer traditionally "royal" male names to choose from.
George and James are the current frontrunners with bookmakers, with odds of between 6/4 and 11/4. "We're very fond of King Georges in this country," she said.
But the peculiar British royal tradition of switching between names may complicate matters.
Prince Charles is expected to be known as King George VII when he ascends to the throne; King George VI was actually christened Albert; and his brother, Edward VIII, who became Duke of Windsor after his 1936 abdication, was known as David by family and friends.
History has also knocked several male names out of the equation: Edward is unlikely, given that scandalous abdication so he could marry American divorcee Wallis Simpson, and the various King Richards, Charleses and Johns are viewed as cruel, tyrannical or just downright unpopular.
"Charles, at 10/1, and John, at 8/1, are very unlikely," Roberts wrote. "Charles is already taken as the name of Prince William's father, and John was one of the worst kings in British history." King John was forced to sign the Magna Carta by his nobles in 1215; he was portrayed as the key villain in "Robin Hood."
"There's no way they would pick Edward as a first name," insists Williams. "And you can't have Henry, after Henry VIII (though of course if Harry came to the throne he would be Henry). My bet is on George Philip William Edward."
In recent years, there has been a move away from classic "regal" names by those on lower branches of the royal family tree.
Prince Andrew and his now ex-wife Sarah "Fergie" Ferguson plumped for the unusual Beatrice and Eugenie for Prince William's cousins. Princess Anne, William's aunt, has two granddaughters by son Peter and Canadian daughter-in-law Autumn Phillips: Savannah (born in 2010) and Isla (born in 2012).
But Joseph said William and Kate were always unlikely to go for more "trendy" options on the lists of popular names. In 2013, the most popular names for baby boys in the UK so far are Noah, Oscar and Oliver, according to babynames.co.uk.
"Obviously other members of the royal family have broken with tradition but the offspring of William and Kate will be a future monarch," she said.
That means, says Williams, "we're not going to see a Chardonnay, or a Plum, or an Apple."
Nevertheless, British betting shops are more than happy to take your money if you fancy a flutter on a more modern or quirky moniker.
If you think the future monarch might name a king-in-waiting after the King, you can always give it a shot: Ladbrokes are offering odds of 500/1 in favor of Elvis, while the chances of the baby prince being named after South Korean rapper and YouTube sensation Psy are a long shot 5000/1.