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Palace officials say the Duchess of Cambridge's birthday celebration will be a "low-key and private" affair, appearing to quash press reports that she will see off her 20s with a fun '80s-themed party, complete with karaoke, in a throwback to her more carefree bachelorette days.
The choice of a muted event seems appropriate: after all, the duchess is not just starting the fourth decade of her life - she is also embarking on her career as a future queen, charged with renovating a monarchy that has become somewhat creaky with age.
"She's done very well, playing a very good supporting role to Prince William and complementing him as part of a team," commentator Robert Jobson said of her first few months as a royal.
"We've not seen much of her, but when she's in public she has performed with aplomb," added Jobson, who is the author of "William and Kate: The Love Story."
The past year has seen momentous changes for Kate, with a fairytale wedding to Prince William, travels around the world and glamorous appearances that marked her transition from commoner to the world's most talked-about princess and style icon.
She has won rave reviews for her sparkle, her elegant sense of style, and her common touch with the public. The media, yearning for a young and beautiful royal, documented - and largely admired - her every move.
On Sunday (local time), they were out in force with the duchess again the centre of attention as she and William took to the red carpet for the premiere of Steven Spielberg's movie "War Horse" in central London.
But now that the excitement around her grand wedding has subsided, she is expected to quietly settle down into her royal duties - and for much of this year, that means helping Queen Elizabeth II celebrate her Diamond Jubilee, without upstaging the monarch in her moment of glory, and also playing a supporting role at the London 2012 Olympic Games.
Until recently, palace officials have been quiet about what exactly her role will be, keen to protect her transition into a fully fledged royal from the glare of the media limelight.
The newlyweds, who live in a remote corner of north Wales, were said to favour a "quieter life" after the massive global media coverage of their April wedding. Outside of a tour of Canada and California in the summer, the duchess has only taken a handful of official engagements.
The former Middleton ventured out on her first solo engagement in October - a private charity dinner for about 30 guests - but is yet to make a public speech on her own.
That is set to change. This week, royal officials finally gave the first insight into her new role when they announced which charities she's supporting, including the Scouts and a group that helps drug addicts. More organizations will follow later, officials said.
The royal family considers patronage of charities an important aspect of their social role, and frequently makes visits and attends events to boost the charities' profiles. William is involved in many diverse nonprofits, while his mother, the late Princess Diana, was well known for her active support for numerous charities including organizations that helped AIDS patients.
Even after her separation from Prince Charles, Diana actively campaigned for a ban on land mines, and visited Angola to champion that cause.
The former Middleton is expected to take on a similar role, eventually designating more charities she wants to be involved with as a way for her to carve out her own niche, based on her own priorities and concerns.
She has already taken on an unofficial role as a champion of the British fashion industry, wearing the creations of British designers at home and abroad, showcasing their work in the best possible light.
On top of such duties, the duchess also has a busy year ahead with the queen's jubilee, a major celebration of the monarch's 60 years on the throne that will take see numerous celebrations throughout Britain and the Commonwealth, peaking in a major celebration in London in early June.
The royals are expected to play a supporting role by traveling overseas to represent the queen. William and Kate are due to journey to Malaysia, Singapore, the Solomon Islands and the tiny Pacific island of Tuvalu as part of the festivities.
The queen and her husband will avoid overseas travel because their advanced years make such trips challenging. The queen's husband, Prince Philip, recently spent time in hospital with a heart problem.
William and his wife have also indicated that they intend to take up residence at an apartment in London's Kensington Palace once his military commitment at an air base in Wales has been met. That will give the likely future king and queen even more visibility in the capital.
Inevitably, much of the speculation about the duchess's future has centred on royal lineage - Is she going to start a family soon? That, however, is anyone's guess, and despite incessant tabloid baby chatter, there doesn't yet appear to be great pressure on the newlyweds to produce an heir.
"It's early days yet, and they're both getting used to their roles," said Jobson, adding that the presence of other young members of the royal household, such as Prince Harry, helps to ease the pressure on William and Kate.
Many of the more senior women in the royal family were mothers in their 20s, but times and expectations have changed - both inside and outside the royal household. By the age of 30, the queen had given birth to two of her four children. Her daughter, Princess Anne, married at 23 and had her first child, Peter Phillips, four years later. Diana also married early and gave birth to William, her first child, at 21.