It was a Nordic fairytale that began with an internet date, developed between the shelves of Ikea, and ended when the Finnish Prime Minister texted “that’s it” to his lover on his Nokia.

Now it is payback time for Susan Kuronen, a 36-year-old divorcée. Only days before the Finnish general election on Sunday, she has published a kiss-and-tell book designed to embarrass Matti Vanhanen, who was once dubbed “the sexiest man in Finland” by Jacques Chirac.

The Prime Minister’s popularity, however, has soared as details of his love affair became public: 49 per cent of Finns want him to continue leading the country, compared to only 11 per cent in favour of Eero Heinäluoma, the Finance Minister and Deputy Prime Minister. Mr Vanhanen, 51, seems likely to be taking his seat at the EU birthday party summit in Berlin in ten days time.

By the standards of Britain’s tabloid press, Ms Kuronen’s disclosures in The Prime Minister’s Bride are less than lurid. “Oven-baked potatoes are what Matti loves above all else,” says Ms Kuronen. “Once after kissing me, he said that I taste even better than an oven-baked potato. That was great!”

The couple would typically take a sauna together, have sex, then the Prime Minister would cook for them both.

Mr Vanhanen — square-chinned, 6ft 2in (1.9m) and divorced from an air-hostess wife — presents himself as a typical Finn. He gives his favourite pastimes as chopping wood and DIY.

After his divorce in 2005, however, Finnish gossip columnists noted that he had a roving eye, text-messaging attractive women. His name was linked with Tanja Karpela, a former Miss Finland who is currently the Minister of Culture.

Ms Kuronen, however, says that her nine-month relationship with the Prime Minister was true love.

He replied anonymously to an advertisment that she had posted on an internet dating site (www.suomi24.fi). They talked through the night in chatrooms — Ms Kuronen has kept the e-mails but the publisher decided not to release the full text — and eventually agreed on a date.

Mr Vanhanen has refused to talk publicly of the affair — one of the reasons why his popularity has increased — but “friends” of the politician let it be known that the couple met in Ikea. He supposedly helped the woman hoist a heavy flatpacked bed on to her trolley.

Ms Kuronen’s book refutes that version and she assumes that the Prime Minister is simply embarrassed about picking up women on the internet. When Mr Vanhanen was delayed at summits he would send her loving text messages, typically signing off with: “Good night from the Chief Executive.”

Love in a cold climate, it seems, is unthinkable without a Finnish Nokia. As the relationship matured, the couple were spotted by tourists outside a log cabin. They took out their mobile phones, snapped the Prime Minister and his lover and sent the pictures around the country. The secret was out.

Ms Kuronen was happy to talk of her love, but Mr Vanhanen promptly broke off the affair with his “That’s it” text message.

The relationship has triggered a debate in Finland about the limits of privacy. Mr Vanhanen and his lover were, after all, single. “The fact is politicians have become our super-celebrities,” said Liisa Jaeppinen, editor of the women’s magazine Eeva. There is little else to compete for tabloid space in Finland apart from the Eurovision-winning band Lordi. And even they wear masks so as not to be recognised in the street.

The Prime Minister’s latest love interest is said to be Merikukka Forsius, a 34-year-old Green politician. They have been seen hand in hand and dancing cheek to cheek. The newly inquisitive Finnish press noted that they both gave presentation speeches for a showing of Al Gore’s documentary film, An Inconvenient Truth.

Times Recommends

• Twitter in trouble over Sarkozy affairs rumour
• North Koreans fear another devastating famine
• Want to be a genius? Practise, says geneticist