They are one of the most famous couples on the planet, one day destined to be Britain's king and queen. And now, the birth of Prince William and his wife Kate's second child caps a momentous four years for the golden couple, completing their journey from student sweethearts to regal domesticity.
Yes, the eyes of the world have again turned on Queen Elizabeth's grandson and his wife, officially known as the Duke and Duchess of Cambridge, with the birth of their second child , a girl.
The couple has cultivated an image as down-to-earth parents ever since William drove his new family home from hospital after the birth of Prince George in 2013, his hands-on approach being in stark contrast to previous generations of royal fathers.
The 32-year-old has proudly boasted of changing George's first nappy, talked about how he balanced sleepless nights with his job as a search and rescue helicopter pilot and admitted "a lot of things affect me differently" since becoming a father.
Now, royal experts say what Prince William and wife Kate really want is as much normality as possible within the confines of being in the spotlight.
Millions of people across the world tuned in to watch their sumptuous wedding in 2011 while the birth of Prince George two years later provoked an international media frenzy outside a hospital in west London.
But while they regularly grace the front pages of newspapers and magazines, and Kate is considered a fashion icon, commentators say what they really enjoy is having a normal family life away from the cameras.
The media crowd around as town crier Tony Appleton (R) makes an announcement of the birth of Catherine, Duchess of Cambridge and Prince William's second child, a daughter, outside the Lindo Wing. (AP Photo)
But the illusion of normality is periodically exposed, such as when it was revealed that taxpayers footed the £4.5 million ($6.8 million, 6.1 million euros) bill for refurbishing their 20-room Kensington Palace apartment in London.
"They've always tried to have the minimum amount of staff, they like to look after themselves as much as they can," royal historian Hugo Vickers told Reuters.
"I'm sure that they'll be again very hands on and very much wanting to be as normal a family as possible."
After their second child, rather than crowns and tiaras, William and Kate will be eagerly looking forward to bath time and changing nappies.
George's birth helped change the public perception of Kate, who was described by novelist Hilary Mantel in 2013 as "a shop-window mannequin, with no personality of her own, entirely defined by what she wore".
She has since gained respect for her battles against acute morning sickness, which hospitalised her during her pregnancy with George, and her reported willingness to stand up to the royal family over George's upbringing.
"The desire to do things their way is underscoring all of Kate and William's decisions," People magazine said in a recent edition.
Britain's royal family has enjoyed a surge in popularity in the last decade, mainly fuelled by its young members, Kate, William and his younger brother Harry, restoring its reputation after the divorce of their parents Prince Charles and Princess Diana, and her subsequent death in a Paris car crash in 1997.
Supporters say they connect with people in a way Charles does not, and their easy-going nature and Kate's background as the first "commoner" to marry a prince in close proximity to the throne in more than 350 years reflected a new version of royalty.
Baby George and Prince William at St Mary's Hospital, where the new royal baby was born. (Reuters)
A poll last month found eight out of 10 Britons liked William and Kate, including three-quarters of those aged 18 to 24.
Author Claudia Joseph said while Prince Charles enjoyed a gilded lifestyle but was kept at arms length by his parents, William and Kate were modern parents, following the model of Diana who would queue with other visitors when she took her sons to an amusement park.
Despite their glittering wedding at London's Westminster Abbey, the couple have always been determined to keep their family life private.
They have vowed to bring up their children out of the glare of the media, which William partly blames for the death of his mother Diana in a car crash in Paris in 1997.
The couple have set up home in Anmer Hall on the grounds of his grandmother Queen Elizabeth II's Sandringham estate in rural eastern England, and William has taken up a new job with the local air ambulance that will keep him out of London.
William and his younger brother Prince Harry suffered through the bitter separation of their parents and the loss of their mother at an early age.
More reserved than Harry, William entered the University of St Andrews in Scotland, where he and Kate met while studying history of art.
The daughter of a businessman and a former air stewardess, the former Catherine Middleton has admitted that she "went bright red" at her first meeting with the second-in-line to the throne in 2001.
Like other couples
William's eyes were reportedly opened during a 2002 university fashion show, in which Kate sashayed down the catwalk in a see-through dress.
Legend has it that spectator William whispered to close friend Fergus Boyd: "Wow, Kate is hot."
By Christmas 2003, they were reported to be a couple and when photographed on a skiing holiday in March 2004, the palace did not deny they were together.
The couple broke up in 2007 but reunited within months and effectively moved in together when William began work at an airbase in Wales.
He finally proposed on a holiday in Kenya in October 2010, giving her his mother's engagement ring.
Their wedding was a display of British pageantry as a million people lined the streets and two billion viewers worldwide watched Kate walk up the aisle.
Now the Duke and Duchess of Cambridge, they undertook their first royal tour in 2011, carving out their own style on a visit to Canada and the United States, mixing ceremonial duties with light-hearted events.
Sailors spell out "SISTER" on the flight deck of HMS Lancaster in a congulatory message to Britain's Prince William and his wife Catherine, Duchess of Cambridge after the birth of their baby daughter. (Reuters)
"I'm sure William does bath time, reads stories to Prince George, and Kate obviously emulates her mother," said Joseph, author of "William And Kate's Britain".
She said William enjoyed being with Kate's parents, away from the usual formality and paraphernalia surrounding the royals.
"He spends a lot of time with them and wants his son to enjoy that side of royal life," she said.
Royal aides also say the couple are acutely aware of the difficulties faced by many Britons coping with financial hardship as austerity measures bite.
Kate regularly recycles her favourite outfits, is seen shopping at supermarkets and according to newspaper reports takes Prince George to farm parks with other mothers and the couple enjoy meals out in local pubs.
For his part, William has so far eschewed a life solely dedicated to official duties.
"It's going to be normal family. Dad goes off to work, comes home and they all have dinner together," veteran royal photographer Arthur Edwards told Reuters.
"He's taken this time out to do a real job. It's as near normal as you can get when you are second-in-line to the throne and to achieve that is something very special and I think he's fought hard to get that."
But critics question how ordinary can a couple really be when they live in gilded palaces and stately homes, renovated at the cost to the taxpayer millions of pounds, and travel the world in luxury.
Kate might not be an aristocrat, but comes from a wealthy middle-class family and enjoyed a privileged upbringing.
Maternity rooms at the private St Mary's Hospital, where the new baby was born, cost well over 5,000 pounds ($7,500), and afterwards the couple were expected to initially return to their London residence, Kensington Palace.
Then they will head to Anmer Hall, the country mansion on the queen's Sandringham estate in Norfolk, to the northeast of London.
Many Britons are worried by soaring property prices, cuts to the national health service, and other economic austerity measures - issues which have figured in campaigning for next Thursday's parliamentary election.
"Should the country be called on to celebrate a royal birth when 3.5 million children are growing up in poverty?" said Graham Smith, the chief executive of anti-monarchist campaign group Republic.
"To single out this birth because they are 'royal' is simply wrong."
(With AFP and Reuters inputs)