He arrived at Number 10 fresh-faced, with an ambitious wife on his arm and a brood of bubbly, smiling children.
by Jackie Storer
BBC News Online political staff
What a contrast the youthful Blair family seemed to make to a nation used to the formality of Downing Street's recent previous occupants: Margaret and Denis Thatcher, and John and Norma Major.
By bringing three children into Britain's most famous address in 1997, Tony Blair appeared, to many people, to breathe new life into the country.
The Blairs arrived in Downing Street in May 1997
One could easily imagine youthful exuberance cocking a snook at Downing Street's staid splendour: works of art, luxurious carpeting and stately rooms mixing incongruously with a whirl of laughter, chatter, toys and mischief.
But while young family life broke the mould at Number 10, with it has come the unerring spotlight of the media.
For the members of Mr Blair's family, growing up, making mistakes, achieving milestones, have all been ready pickings for Britain's newspapers, TV and radio broadcasters.
Not for the Blairs a quiet retreat behind closed doors. With public life has come publicity, and much of it very unflattering.
Before moving into Downing Street, Tony and Cherie Blair vowed to bring up their children Euan, Nicky and Kathryn, in as normal an environment as possible.
But with the birth of another son Leo, high profile in-laws, their choice of schools, MMR jabs, teenage drunkenness and a controversial property deal, brand Blair has quickly turned into a veritable soap opera.
The story about an alleged plot to kidnap Leo by fathers' rights campaigners is just the latest episode in the Blair family's life in the headlines. Here are some of their highs and lows.
SCHOOLING AND THE EUAN FACTOR
Euan Blair's first scrape with the headlines comes at age 10 when his parents decide to send him to the London Oratory, a grant-maintained school in Fulham, south west London.
Labour party activists are up in arms, saying the decision is a betrayal of the party's long-held opposition to schools opting out of local authority control.
Mr Blair responds by saying "his education should come before any political convenience".
Blair 'used the Euan factor' to decide the contents of the Dome
Nicky joins his brother at the London Oratory, while their sister Kathryn is sent to the Sacred Heart comprehensive high school in nearby Hammersmith.
Later, Euan is reportedly used by his father as a way of keeping government projects in touch with the teenage mind.
The "Euan Factor" is considered during high-level discussions about what should go in the Millennium Dome.
Mr Blair is said to have demanded to see evidence that exhibits at Greenwich would excite his son, then aged 13.
Three years later and Euan gives Mr Blair a different insight into what many would say is the typical British teenager when he is arrested for being drunk and incapable in London's Leicester Square after celebrating the end of his GCSE exams.
NOVEMBER, 1999 - BABY SHOCKER
Tony and Cherie surprise the world with news they are expecting a fourth child.
Leo was the first baby born to a serving PM in 150 years
Mrs Blair, 45, and her husband are said to be delighted, though the news came as a "total shock".
The child's due date is nine months after the family's month-long holiday in France and Italy in 1999.
Mrs Blair breaks the news of her pregnancy to her husband that autumn, on the eve of the Labour Party conference in Bournemouth.
JANUARY 2000 - CHERIE'S TICKET BLUNDER
Mrs Blair is fined £10 after she fails to buy a ticket for her journey from Blackfriars to Luton, where she sits as a recorder at Luton Crown Court.
Downing Street says she had insufficient cash for the £9.60 ticket and had been unable to use her credit card at the ticket machine at the London station as it took only cash.
MARCH 2000 - NANNY GAGGED
Mrs Blair slaps an injunction on the Mail on Sunday to block the publication of the memoirs of the family's former nanny Rosalind Mark.
Although barred from spelling out the details, columnists gleefully recount that the nanny's literary efforts revolve mainly around the contents of the Downing Street fridge.
Mrs Blair later drops legal action against Ms Mark and her agent, Jonathan Harris; and settles with the newspaper's publisher.
20 MAY, 2000 - THE BIRTH OF BABY LEO
Leo George Blair, named after Mr Blair's father, is born four days early at London's Chelsea and Westminster Hospital, weighing 6lb 12oz.
Shortly after Leo's arrival, Mrs Blair says she is "tired but full of joy".
"It is so long since we had our other three children that I had forgotten quite what an ordeal those last few hours of labour can be," she says.
Leo is a 'lovely little kid', says Blair
Mr Blair, who describes his new son as "gorgeous" and "a lovely little kid", says: "The thing is, you forget how tiny they are and also changing nappies in the middle of the night."
Leo makes his first "public appearance" when he is just weeks old and begins his global travels with a visit to Portugal with his mother - who is still breastfeeding him - to stay with the British ambassador at his official residence.
During his early days he visits the Queen at Balmoral and is held by then US President Bill Clinton at a UN summit in New York, before being passed to French President Jacques Chirac.
But he is soon embroiled in a row over privacy when "unauthorised" photographs of him are used by newspapers in spite of pleas by the Blairs.
A set of 14 pictures of the Blair parents and baby, taken shortly after Leo's birth, are made available to publications the world over.
However, they have to pay £500 for Mrs Blair's chosen charity each time one is published, raising thousands for Breast Cancer Care and the Sargent Cancer Care for Children.
DECEMBER 2001 - BLAIR PRESSED OVER MMR JAB
Mr Blair is pressed by then Liberal Democrat leader Charles Kennedy to end speculation about whether his youngest son Leo has been given the controversial MMR jab.
The prime minister refuses to say whether Leo has had the vaccination, claiming this is to protect his privacy.
The Blairs will not reveal whether Leo has had MMR
"The suggestion that the government is advising parents to have the MMR jab whilst we are deliberately refraining from giving our child the treatment because we know it is dangerous is offensive beyond belief," says Mr Blair.
Mr Kennedy suggests the comments are an admission that Mr Blair's son has probably had the injection and says he could easily put the issue to rest by confirming that is the case.
However, Mr Blair says in a statement: "It is not true that we believe the MMR vaccine to be dangerous or believe that it is better to have separate injections, or believe that it is linked to autism.
"On the contrary, the vaccine which is used throughout the world, helps prevent the spread of diseases that can, if contracted, cause very serious damage to children."
SEPTEMBER, 2002 - BLAIR ON FAMILY LIFE
Mr Blair tells a magazine how his son Leo, two, watches the classic musical Chitty Chitty Bang Bang every morning.
Says the prime minister ruefully: "I enjoyed it the first three times ... Now I know all the words to all the songs."
Family keeps your feet on the ground, says Blair
Mr Blair says he likes to play the guitar, although he adds: "I'm not very good at it." He also enjoys watching TV with his children, especially The Simpsons.
"Keeping your family life is the most important thing, it keeps your feet on the ground," he says.
"The children cope with having a prime minister for a father because we're a normal family."
DECEMBER 2002 - 'CHERIEGATE'
Cherie Blair apologises for the embarrassment she causes in buying property with the help of convicted fraudster Peter Foster.
After several days of press reports about her links with the Australian conman in the purchase of two flats in Bristol, Mrs Blair makes a tearful 10-minute statement admitting she made mistakes in the controversial property deal.
She would never do anything to harm her husband, her children or the Labour government, she says.
Cherie is in tears as she apologises for embarrassment
She had not known Mr Foster had been to prison and had she known the full details of his past, she would not have allowed herself to get into this situation, she adds.
Mrs Blair says she never thought that Mr Foster, boyfriend of her friend and "style guru" Carole Caplin would "land me in this mess".
While she has a "special position" as wife of the prime minister, she says: "I also know I'm not superwoman".
Downing Street accuses the media of a "deliberate campaign of character assassination" against Mrs Blair.
On occasions, Tony Blair has been given the benefit of advice from his father-in-law, the actor Tony Booth.
Best known for his role in long-running TV sitcom Till Death Us Do Part, Mr Booth, father of Cherie Blair, has offered his opinions on the state pension and disability reforms.
Tony Booth, father-in-law and thorn in the side
In September 2000, Mr Booth calls on the prime minister to restore the link between the annual pension rise and average earnings, which he says will free thousands of pensioners from reliance on state benefits.
He also accuses Mr Blair of going in to Kosovo with his "hands tied, blindfolded and telling your opponents your plans".
There have also been plenty of half-sisters of Cherie popping up in the papers over the years.
Even taking a break together has not been without controversy for the Blairs.
In recent years the family has holidayed in Egypt, Cumbria, Tuscany and Siena. In 2003 and again last summer they holidayed at a £2m villa belonging to singer Sir Cliff Richard on the island of Barbados.
While the Blairs have paid for many of their trips, they have faced criticism about who has funded some of the jaunts.