It's a story that many couples today can relate to. How do you keep a marriage together with both partners working and all the pressure of child-care and lack of time? Who is going to go to the supermarket, cook dinner, earn the most money?
The answer, the experts say, lies in the art of communication and old- fashioned respect. It's the kind of thing that Tony Blair and Cherie Booth know about. In a country where four in 10 marriages fail, the success of the First Marriage has not gone unnoticed. "Young men and women can really relate to them as a couple," said Helen Wilkinson, author of a report on marriage last year for the think-tank Demos. "They are seen as kind of having it all. On a symbolic level I think they are hugely significant."
Their story begins in 1977, and romantics should note that it was not love at first sight. Last year the Blairs, in a rare interview as a couple, told the American television programme 60 Minutes how they met. "We were sort of sitting next to each other at something and discovered that, in fact, we were both pupils with the same barrister," said Tony. "Which didn't please me at all, because I had been assured I was going to be the only one," said Cherie. So, the interviewer said, were you rivals? "Hmmm, a little bit," said Cherie. "I suppose we could have been," said Tony.
Any couple hearing those answers would have to smile, not because of what was said but what was not said. Rivals? I should think so - both in career and in politics - but the wonder is that they have managed to transform their competition into co-operation. It hasn't been achieved without compromise.
Marriage may have been easier in the old days when wife and husband knew exactly what was expected of them. "When you don't have those roles there is much more room for conflict," says Penny Mansfield, of the charity One Plus One, which is conducting research on this subject for the Government. "Now couples have to make it up as they go along."
Tony and Cherie remained rival law students for almost a year. Then Cherie invited him to a Christmas party and they ended up playing a game that involved passing a balloon to each other through their legs. Suddenly, Tony saw his prickly and clever colleague in a different light. "The next day we went out to lunch and hours later we were still there," said Tony in an pre-election interview last year. "I found her immensely physically attractive and I wanted her as a friend as well."
Cherie was not so sure, but Tony Blair doesn't give up easily. "Once you succumb to Tony's charm," she has said. "you never really get over it." It was the biggest decision of her life.
They became engaged in 1979, during a holiday to Italy and married on 29 March 1980 at St John's College in Oxford. Like most couples now, they married relatively late (he was 26, she was 25). This trend has continued, with the average age of marriage going up over the past four years (now it is 27 for women, 29 for men) while the average first age of sexual intercourse has dropped four years to 17. And, also like most couples now, the Blairs have always been a dual career family. Somehow, they have made it work.
Many do not. These days, Penny Mansfield says, a satisfying marriage is not so much a romantic relationship as a partnership based on shared goals and respect. "The modern marriage requires three things," she says. "You've got to communicate effectively. You can't simply not say anything to each other and get on with your roles. Secondly, you've got to negotiate fairly. Each person must feel as if their needs have been regarded. Three, you need to manage conflict safely and you mustn't allow them to become personal and nasty."
For the Blairs, compromise began almost from the beginning. Early on, Cherie decided to quit competing directly with him for a tenancy in Lord Irvine's chambers and joined the chambers of libel lawyer George Carman instead. Tony Blair stayed put. Their next challenge would come in the political arena. Both were passionate about politics (she had joined the Labour Party aged 16 in 1970, he waited until 1975) and decided that each would try to get elected to Parliament. Then they are said to have made a deal: whoever made it first would continue in politics while the other supported the family. Both stood for election. Cherie almost lost her deposit in Thanet North. Tony won in Sedgefield in 1983.
Fifteen years later, the deal still stands. It has lasted through the births of three children and much more. Cherie Booth - as she is known by colleagues - has made her family well-off if not rich. There are signs, too, that there have been negotiations over his career, particularly in his decision not to contest the deputy leadership under John Smith. "When it came to whether or not he was going to run for the deputy leader's job, Euan said he was glad that Daddy has chosen to spend more time at home," Cherie told interviewer Barbara Amiel in 1992. "I think Tony is incredibly talented and I want him to succeed - he's got an incredible amount to offer - but we've got young children and they need to be protected."
John Smith's death in 1994 forced the decision that the Blairs had thought would wait until their children were grown. Tony Blair told an interviewer last year that he heard the news while driving along the Great Northern Road in Aberdeen. "I had to speak to Cherie before I made any decision. I got back to London as quickly as I could." In Islington, he and Cherie sat down and talked. "Cherie said, 'You didn't ask for this, you didn't plan it, but it's here and you've got to do it'," said Tony. "I said: 'Look outside the front door. There were journalist and photographers and camera crews. This is what we're going to expose the children to'."
In the end he listened to his wife, but he has stuck to his part of the bargain too. At a reception to mark her husband becoming leader, a local councillor noted that she would be giving up work if her husband became PM. "And can you tell me one good reason why I should?" she demanded. In 1995 she became a QC. "I would love to be a judge," she said. She is the first working mother to reside in Downing Street. "I'm full of admiration for Cherie. How she manages to do these cases and keep everything separate, I don't know," said Linda McDougall, author of Westminster Women and wife of Austin Mitchell MP.
We may never know much more about what makes the First Marriage tick although many, including Linda McDougall, enjoyed seeing a glimpse of the Blairs at home last month when a spoof caller to No 10 was told to just hang on a minute while Cherie went to fetch the Prime Minister. "I thought that was an interesting insight. It sounded fantastically normal," she said. "It's great that they really do have their breakfast together and worry about the athletic kit and the socks."