'I never wanted marriage'

Her next task - she has always done a lot of charity work, especially for cancer - is climbing Mont Blanc to raise money for motor neurone disease, which Opik's father died from. "Lembit can't do it because he broke his back paragliding a few years ago, but I am committed to raising the money. I saw Lembit's father go into decline and it was dreadful. He had this wonderful mind until the end but his body shut down and it was awful."

Opik has had a terrible year. "We were going to get married before the general election," she says, "but his father died and then his brother Endel dropped down dead and then his best friend died. It's not the right time to have a celebration."

The "will-they, won't-they" question has been much reported on in gossip columns. "To be honest," says Lloyd, "I've never really been the marrying type so it doesn't bother me. I'm a fainthearted feminist. My mother, Barbara, was a militant, independent woman. She was the president of the Welsh Union of Teachers and raised me to believe that marriage and children were not everything for women."

So why do it now? "Because I love him!" she says. What about children? "I've never wanted children," she says. "I was not brought up to aspire to that. I work hard and see my friends and walk a lot in Wales, so I don't feel a gaping hole in my life."

What about her fiancé? "It's not an issue," she says, waving her hands around. "I always use my hands a lot!" Suddenly she leans towards me so much that I wonder if she's going to break. "I'm Welsh. We're the Italians in the rain!"

Being Welsh is important to her. She set up SWS - Social, Welsh, Sexy - with entertainer Stifyn Parri some years ago. "It's a networking thing," she tells me. "We were at the Groucho and we came up with the idea of SWS. People like Bryn Terfel and Siâšn Phillips are now patrons." You don't have to be all three, though Sian is.

But Opik isn't Welsh, is he? "No, he's Estonian and was brought up in Northern Ireland, but his constituency is in Wales." She met Opik some years ago at a party. "We were at one of those politiciansmeet-the-press parties. I met Lembit and we talked for hours."

But they didn't meet again for a couple of years. "I lost a ring and he rang me and said, 'I've got your ring!' He had found it at the party but then lost it himself. I had an extra ticket to the Proms, so we went together and that was it."

That was four years ago. Two years later he proposed. Why does she love him? "He is a great man, a live wire. He sticks to what he believes in even if it makes him unpopular."

For a while, Opik - MP for Montgomeryshire - looked as if he would be the saviour of the Lib-Dems, but he slightly blotted his copy book first by claiming that the earth is under threat from asteroids and second by supporting Charles Kennedy when everyone was abandoning him. "He was very loyal to Charles," says Lloyd, "and then to Mark [Oaten] and he's never changed his mind on that."

Does she intend to be the perfect politician's wife? "No," she says, laughing again. "I am like my friend Ffion [Hague]. We both have our careers and our lives. I'll be there when Lembit needs me but there is a strange assumption that because your husband is a Lib-Dem MP you must be a Lib-Dem supporter." So she isn't then? "My parents were Left-wing. My father was an artist. My mother was a teacher. We were not a Liberal family in the political sense."

So what was Sian Lloyd's childhood like? She grew up near Bridgend in "a lively family household" with her parents, brother David and sister Ceri. "My parents wanted us to be able to express ourselves, so we did. We didn't speak Welsh at home though, only English."

She was taught Welsh at school and did Celtic studies at university in Cardiff. While she was there she met Mark Cavendish, a relative of the Duke and Duchess of Devonshire and now a businessman. They were together for 14 years.

She had a rarefied time with Cavendish, whose family seat is the majestic Chatsworth in Derbyshire. "Have you been to Chatsworth?" she asks."It's beautiful." Cavendish managed her career - watching her shoot up from reporter at Cardiff Broadcasting Company through to Worldwide TV News and then on to becoming an ITV weather presenter. "Oh Mark," she says sighing. "He's a lovely man."

But Lloyd got involved in a public love triangle when she struck up a relationship with Gulf war cameraman Greg Taylor. "That was over 10 years ago," she says. "These things happen but everyone works it out."

So, what's next? "I love my job but do I like people coming up to me in the street asking what the weather will be like for their sister's barbecue? I don't mind but I don't do long-range forecasts." Not even for herself ? "I'll do my job," she says, smiling, "raise money for motor neurone disease and, if we can find the time, Lembit and I might even get married."