On Wednesday, less than 24 hours after Manchester-based businessman Micheal Wall described her current sociopolitical status as "out of the circle", she did her star turn at Dublin Castle as Madame Le Meritocracy. In a voice devoid of a pigeonholing accent, she alternately cooed at and chided the learned tribunal counsel, addressing the pair of formidable silks as "Henry" and "Des" with imperturbable we're-allequal-citizens-here republicanism.

The sharpness of her blonde asymmetrical bob contrasted with the vulnerable softness of her baby-pink boucle suit. The combination announced to her transfixed audience that here was a feminine woman with her gender's version of the "balls of steel" boasted by a previous occupant of the planning tribunal witness box, Frank Dunlop. The beauty consultant had come with her iron fist clad in a velvet glove.

"It was she who removed herself from the circle, " a confidante disclosed later, alluding to the fractious position she held at the heart of the Drumcondra Mafia for nearly two decades. "She has broken all the old ties and moved on. She keeps contact with her own non-political friends, not Bertie's. She's adjusted to her single life. The problem for her, though, is that he still hasn't gone away.

The difference between them [at the planning tribunal] is that she is only a witness. She is not being investigated.

Unlike him, she can walk away from the castle and put it behind her. They have a civil relationship. It's not what you'd call loving."

To outsiders, Bertie & Celia are Ireland's Taylor & Burton: they can't seem to live together, can't seem to live apart.

Though it is commonly said they were together for 15 years, a friend of Larkin's calculates that "it was closer to 18 years".

Ahern had married Miriam Kelly in 1972 and he was legally separated from the mother of his two daughters in 1993.

He said that his heavy workload as a TD and as Lord Mayor of Dublin in 1987 had caused the break-up.

During an attempted leadership putsch in Fianna Fail in the early 1990s, former minister and Albert Reynolds ally Michael Smith propounded: "The people should know where the taoiseach sleeps at night." It was a pointed attack on Bertie Ahern's messy private life and it compelled him to make two defining decisions . . . though marrying his girlfriend was not one of them, as a tenet of Catholic principle.

First, he gave strategic media interviews in which he talked about the disintegration of his marriage, allowing Celia Larkin to be gently introduced to Fianna Fail grassroots as the permanent woman in his life. Second, he needed to establish a home for himself, and this was the task he handed to his girlfriend.

"Celia was never only a wife figure for Bertie, " her confidante elaborated. "It was she who organised his legendary constituency machine. She gave up her own political ambitions to put everything into his career. She'd stood in the council elections in the '70s and came within a handful of votes of getting a seat."

At the planning tribunal on Wednesday, where her former partner's second life-defining decision to acquire a home has thrown them fleetingly together under the spotlight, Larkin outlined how she used to organise her partner's famous annual fundraising dinners at the Royal Hospital in Kilmainham and, later, at Clontarf Castle.

Since the couple split in August 2003, Ahern, 56, has been linked with several women. His longest-lasting liaison was with Anna Bogle, whose husband, Brian, had been a friend of Ahern's until his death from cancer at the age of 49.

That relationship commenced within weeks of the first rumours of Ahern's and Larkin's separation and is now reportedly over.

Larkin, 48, does not have a man in her life at present, according to a friend, and her only reported post-Ahern romance, with Castleknock shoemaker John Rooney, was shortlived. Both men attended her mother's funeral mass at St Canice's Church in Finglas in October 2003. She has rejected repeated invitations to tell the story of her life, with Ahern, with one newspaper offering her a "five-figure sum". In December 2003, she vowed: "I will never talk about my private life, not for anything."

Three Christmases earlier, her partner had displayed blundering insensitivity by declaring to a national newspaper that he would never marry Celia Larkin. "He's a man's man. He'd rather be drinking Bass with the lads down in the pub, " rationalises a friend of Larkin's, failing to disguise his own disdain for "the way he treated her".

When the taoiseach is counting his blessings, he undoubtedly gives thanks for having been loved by a loyal woman.

Since they parted, he has shown his indebtedness to her with a media-sensation visit to her new beauty salon in Limerick's Castletroy Park Hotel where he told 300 guests: "When Celia puts her mind to something, she will move heaven and earth". In her replying speech, she said: "Bertie has always been a rock of support."

She may or may not have been referring to his insistence that she be appointed to the inaugural board of the National Consumer Agency. When it emerged that the taoiseach had appended her name to the list of nominated directors after the other state appointees had been announced by enterprise minister Micheal Martin, the Opposition accused him of "cronyism". Green Party leader and cabinet colleague John Gormley fulminated that appointments should be made on the basis of "what people know, not who they know". Larkin has since been reappointed to the National Consumer Agency, along with fellow director Eddie Hobbs, Fianna Fail's bete noir on the economic front.

Compared to the days when she travelled the world in the government jet as the taoiseach's official consort . . . toasting St Patrick's Day in the White House, strolling hand in hand along the Great Wall of China . . . Larkin's new life is pedestrian. She lives in a rented house in Killaloe, the serene east Clare village which has attracted the Eurovision singer Brian Kennedy and comedian Brendan Grace. Her sister already lived in Killaloe with her own family, lending a readymade social structure when Celia moved there in April 2006.

"She's a very nice woman. People don't bother her, " said a fellow Killaloe resident. "Generally, there's huge compassion for her."

She spends two days a week in Dublin, overnighting in a house she owns in Castleknock and attending to business in the Drumcondra branch of Beauty at Blue Door, up the road from Ahern's constituency office, St Luke's. Her beauty salon business has been slow to show substantial profits but her regular guest talks to women's groups around the country are highly lucrative. She also continues to make celebrity appearances: attending the Killaloe scouts' fundraiser, opening an art exhibition at the Hunt Museum in Limerick, judging ladies' day fashion contests at race meetings.

Celia Larkin cuts the figure of a well-to-do business woman. She drives a black 2006 Mercedes 180, is a director of the voluntary housing agency, Cara, plays tennis at Castleknock Tennis Club and walks in the Clare countryside to keep fit, enjoys cooking for friends and indulging her passion for fashion. Dublin couturier Jen Kelly is one of her closest friends, along with Michael Ronayne, a former Fianna Fail press officer and adviser to Sile de Valera, and barrister Mary Kerrigan, originally Larkin's codirector in Beauty at Blue Door and now working for Charlie McCreevy in Brussels. Two other good friends are Kay and Hugh O'Flaherty. When Larkin was still the taoiseach's partner she made a conspicuous visit of support to the besieged couple's home in the days before Supreme Court judge Hugh O'Flaherty resigned over the Sheedy affair, which came close to destroying the government.

Loyalty and resolve are, according to one of her friends, "her two outstanding characteristics". Both traits were encapsulated in an encounter in the ladies' toilets during the lunch adjournment in Dublin Castle on Wednesday. A journalist, recognising the woman washing her hands at the sink beside her and thinking she had landed the scoop of the day, asked the witness: "Is it awful for you?" Larkin smilingly responded, over and over again, with enquiries about the journalist's own welfare, her family, her summer holidays, her job. . .

As one man observed when she departed at the end of the day: "You can see why Bertie was with her. She'd have been well able for him."