Prince William and Kate Middleton, the Younger Years

April 11, 2011— -- The dream of marrying a handsome prince is, for most little girls, just a dream. But for England's own small-town girl, Kate Middleton, the fantasy will become a reality when she weds Prince William April 29.

The union makes an alliance that would once have been impossible. Middleton will be the first commoner to marry into the British royal family in 350 years.

"I cannot believe that any of Kate's ancestors would ever have imagined that she would one day be marrying the next-but-one in line to the throne," said Claudia Joseph, author of "Kate Middleton, Princess in Waiting."

But Middleton's family has been rising in society for 100 year.

"What's extraordinary about Kate is the fact that her ancestors descend from incredibly impoverished mining stock in the pits of County Durham in the north of England in the 19th century," Joseph said.

Her great-grandfather, Thomas Harrison, was determined to escape the mines and became a craftsman and his ambitious daughter, Dorothy, took the family up another rung on the social ladder.

"Kate's grandmother was nicknamed 'Lady Dorothy' in the family; she was a bit of a snob, she dragged the family up and married a builder," Joseph said.

Her daughter, Carole, Kate Middleton's mother, became a flight attendant and also married up to Michael Middleton, a flight dispatcher whose family tree included lawyers and wealthy merchants.

Carole and Michael Middleton's first child, Catherine Elizabeth, was born Jan. 9, 1982. And not even "Lady Dorothy" could have imagined the heights her granddaughter would scale.

Five months later, on June 21, 1982, Prince William was born to Princess Diana and Prince Charles with all of the pomp and circumstance befitting the apparent future king. William was on constant display, preparing for the monarchy.

The Heir and the Spare

"He's very aware of his surrounding, the people who he surrounds himself with, his duty in life," Katie Nicholl, author of "William and Harry," said. "He is far more serious than his younger brother, Harry."

Andrew Morton, author of "Diana: Her True Story in Her Own Words, said, "William has always been groomed slightly differently, to Prince Harry. And he's always been naturally more serious, rather more solemn.

"[He was] aware from a fairly early age, that he had the weight of expectation, and the weight of the monarchy, on his rather slim shoulders."

Still, Princess Diana wanted to give her sons a normal life, educating them in schools among their peers, taking them out to amusement parks, giving them a chance to know what life was like outside of the palace walls.

But the cameras were constantly waiting and when William went to school for the first time, the press went too. Ken Wharfe, who was on Princess Diana's security team and was with the prince that day, said, "Diana said to him in the car, 'Now listen, William, you know, there are going to be a lot of press and photographers there so you need to be on your best behavior.'"

And William pulled the cap down of his hat and said, "'I don't like 'tographers,'" Wharfe said.

Kate Middleton, the Student

While William was fending off press, Kate Middleton was growing up in the idyllic Berkshire countryside. The only photographers in her life were her parents taking snapshots.

A happy child, she played hockey and was a member of her local brownie troop. After her mother started a successful party-supply company, the family moved to the affluent village of Bucklebury, where Kate went to a local private school.

Like girls across England, the ones at Middleton's school had set their sights on young Prince William.

"You'd overhear them talking about it," said Kingsley Glover, a fellow student at St. Andrews Prep School. "You'd hear them saying, 'Oh, wouldn't it be great if you ended up marrying the prince.'"

The next year, Middleton entered one of England's most exclusive and expensive boarding schools, Marlborough, where she blossomed into a beauty and was popular with the boys, but never went too far.

The Death of Diana

"She's always been dignified even when she was at school. She's always been one of those who, yes, she'll join in the fun but she'll never put a toe out of place," author Morton said.

At Marlborough, Middleton met many young aristocrats, including several of William's polo-playing friends who now were her friends, too. Middleton's world was getting bigger and more blue blooded while William's was falling apart.

His parents' crumbling marriage was the top story in the tabloid press.

As photographers chased Princess Diana through the streets of Paris Aug. 31, 1997, the car in which she was traveling crashed in the Pont de l 'Alma tunnel. Princess Diana would die soon after being cut from the mangled wreckage and Prince Charles would be left to deliver the news to William and Harry that their mother was dead.

After his mother's death, speculation surrounding the paparazzi's role in the tragic car crash only fueled William and Harry's distrust of the media.

Colleen Harris, who became press secretary to Prince Charles, Prince William and Prince Harry after Diana died, said, "I've worked for prime ministers and given advice, and they were very willing candidates, whereas William was always a very questioning candidate. They were quite suspicious and really didn't want to engage that much."

As soon as William graduated Eton, he was able to escape from the gaze of the paparazzi and head off to his gap year, a year many British students take before heading off to college. It was a time for him to explore the world and contemplate his future.

But the future held something he couldn't imagine. A year later his life would intersect with Kate Middleton's: she the representative of 100 years of social aspirations, he an heir to a throne, scarred by scandal and divorce. They would form a bond made in childhood dreams.

For more on Prince William's and Kate Middleton's childhood years, tune into a Barbara Walters special. "The Royal Wedding: A Modern Fairytale" April 18 at 10 p.m. ET.