London (CNN) When Boris Johnson's girlfriend Carrie Symonds joined the entourage of staff who gathered outside 10 Downing Street to watch his first speech as British Prime Minister, witnesses reported that photographers went "bananas."
Until now, the 31-year-old former Conservative party communications official has done a pretty good job of staying out of the media spotlight -- rarely seen on the campaign trail and steering clear of historic moments like meeting the Queen.
Keeping a low profile for the past 18 months as girlfriend of a senior politician is one thing. But doing the same as partner of the Prime Minister will prove more difficult.
In recent days, the British media has gone into overdrive. From her living arrangements (will she move into Downing Street?) to her involvement in diplomatic affairs (will she accompany Johnson on foreign trips?), every aspect of Symonds's relationship with Johnson has been the subject of speculation.
Downing Street told CNN it did not know whether Symonds would move in to the famous residence.
These are uncharted waters for the British establishment -- never in living memory has a UK Prime Minister had an unmarried partner while in office. Unlike US first ladies, UK first partners have no strictly defined role, and it will largely be up to Symonds to shape it.
"It's kind of made up as they go along, so it's very dependent on the personality of the particular person, said Professor Tony Travers, director of the Institute of Public Affairs at the London School of Economics.
Travers pointed to the way former Prime Minister Tony Blair's wife Cherie continued her career as a lawyer and "was very much her own person with almost nothing to do" with her husband's job.
Meanwhile Theresa May's husband Philip stood by her side as she delivered her final speech as Prime Minister. "He decided to have a supportive, low profile, and the press pretty much left it at that," said Travers.
The new Prime Minister is also unusual for having a partner who had a political career -- long before she met Johnson. The daughter of Matthew Symonds, a co-founder of the Independent newspaper, and the paper's lawyer Josephine McCaffee, Symonds had a privileged upbringing in southwest London where she attended a private girls' school.
Symonds studied theater studies and art history at the well-respected University of Warwick, before working as a press officer for the Conservative Party in 2010 and quickly rising up its ranks.
She was part of the campaign team that helped to get Johnson re-elected as mayor of London in 2012.
At 29, Symonds became the youngest-ever director of communications at the party, and analysts say she's been crucial in tidying up Johnson's famously disheveled persona during the leadership campaign.
"Since she's come on the scene he's become a much trimmer figure, he's lost weight, he's had his hair cut ... he's definitely smartened up his appearance," said Caroline Wheeler, deputy political editor at the Sunday Times newspaper.
Symonds is a "very established political communicator," Wheeler added. "She'll know how to keep him on message."
Throughout the leadership campaign Johnson was "very careful" about whom he spoke to, said Wheeler, doing few newspaper interviews and shunning some of the major TV debates.
"He's been a lot more disciplined figure and lots of people have credited Carrie with that transformation," Wheeler said.
Symonds now works as a senior adviser to conservation charity Oceana, and her Twitter feed is filled with stories ranging from overfishing to banning trophy hunting.
Some analysts believe she will have the PM's ear on the climate crisis and animal welfare, an issue that Johnson unexpectedly touched on during his inaugural speech.
"She'll influence policies, particularly the environment," said LBC radio broadcaster and political commentator Iain Dale. Johnson has been "talking a lot about climate change during the campaign," he said.
Symonds has also spoken out about other issues important to her. Barely out of her teens, she spoke publicly about her encounter with John Worboys -- known in the UK as the "taxi cab rapist" who is thought to have assaulted at least 100 victims.
At 19, Symonds caught a lift with Worboys to her home in west London and during the ride he offered her alcohol -- much like the other spiked drinks he gave his victims. She said that as a result, she does not know what happened afterward.
Symonds waived her anonymity in the case, telling a number of British papers about her ordeal. She also helped to launch a judicial review after the parole board decided Worboys was no longer a threat.
The review later found Worboys still posed a major risk to the public, and would remain in jail. The justice system had "let us down," Symonds wrote in the Evening Standard. "Finally we've been proved right."
Today, Symonds is in British newspapers for different reasons.
At 55, Johnson is more than two decades older than her. He is still married to his wife of 26 years, Marina Wheeler, with whom he has four children.
The couple separated last year and reports of Johnson's alleged extra-marital affairs -- and children out of wedlock -- have long graced the pages of the UK papers.
Johnson has never publicly addressed the issue of his extra-marital children. CNN contacted Johnson's office for comment but had not received a reply at time of publication.
Given Johnson's complicated private life, his relationship with Symonds "has got all the ingredients for the type of thing tabloid newspapers love," said Travers.
But their relationship is also a reflection of modern Britain, said Wheeler. "There are lot of people who choose to live together without being married," she said. "And I think it's important that those who are running the country, reflect what many people in this country are doing."
The couple's relationship was put under the spotlight like never before during the leadership campaign after police were called to an argument at Symonds's south London flat.
Neighbors recorded Symonds telling Johnson to "get off me" and "get out of my flat." Police said that officers arrived and "spoke to all occupants of the address, who were all safe and well."
The incident raised questions about whether Britain's next leader owed the public an explanation for what happens behind closed doors.
"The British press is supposed to operate on a 'public interest' basis," said Travers. Meaning "does the prime minister's private life in any way impinge on their capacity to do their job?"
With the UK in the grip of its worst political crisis in decades, Johnson is under huge pressure to deliver Brexit by the October 31 deadline. The PM probably feels he can do without the extra focus on his private life.