Charlene Wittstock will go from Olympic swimmer to princess when she marries Albert of Monaco tomorrow. But tales of a last-minute bolt suggest that life among the scandalous Grimaldis is no fairytale, says Alistair Dawber

If it all goes to plan – and for a moment earlier this week that looked like a very big "if"– the other royal wedding of the year takes place in Monaco tomorrow, much to the relief of officials at the Royal Palace in Monte Carlo.

It is not just that the bride, the South African former Olympic swimmer Charlene Wittstock, was rumoured to be getting cold feet on Tuesday, amid claims that she had hot-footed it to nearby Nice airport and asked for a one-way ticket back to Johannesburg. It is hoped the wedding will signal that Albert II, one of Europe's last playboy princes, has decided finally to settle down. The palace was forced to issue a statement denying the story in French tabloid L'Express that 33-year-old Miss Wittstock was having second thoughts and that it took "infinite persuasion" to get her back to the principality.

"These rumours only serve to gravely hurt the image of the Sovereign and that of Miss Wittstock and bring major harm to this happy event," said a palace spokeswoman. The palace did not, however, gag the magazine, but started a manhunt to find out who was the mole that alerted the press.

Following the centuries-old truth that the people must see their rulers, Miss Wittstock was quickly sent on walkabout to "prove" she was happy to be there. At the very least, with the wedding reportedly costing £50m, best leave nothing to chance.

L'Express, incidentally, stands by its story and editor, Renaud Revel, said no attempt had been made to get the story removed from its website.

Albert ascended to the head of the House of Grimaldi in 2005 on the death of his father, Prince Rainier. Hitherto one of Europe's most eligible bachelors, the 53-year-old counts Brooke Shields, Claudia Schiffer and Naomi Campbell among his exes.

Of course, another commoner royal bride – and her omnipresent younger sister – has done much to take the limelight off Miss Wittstock, a Zimbabwean-born swimmer who competed for her adopted South Africa in the 2000 games. But that is where the connection between her and Kate Middleton, Duchess of Cambridge, come to an end. Kate, who is frightfully posh anyway, has won over the people in a way that Charlene has not.

There will be partying in Monaco during the two-day jamboree and even The Eagles have been flown in to entertain the glitterati (their hit Hotel California might have to be vetoed in the light of Charlene's rumoured bolt: "You can check out any time you like, but you can never leave...").

But to the extent that the tiny principality has a population (the latest count put it at 35,000 and 360,000 bank accounts) beyond the tennis players, stars of motor racing and tax-avoiding hedge fund managers, Miss Wittstock has struggled to connect with Monegasques. Speaking to Tatler magazine last year, she admitted to not enjoying all aspects of life in the principality: "The people I mixed with in Monaco didn't relate to my South African mentality or humour. Of course, I've been subject to jealousy, but that comes with the territory. Although I have met some wonderful people since I've been living in Monaco, I regard them all as acquaintances. I only have two people I consider friends here."

She might agree with W Somerset Maugham's assessment that Monaco is "a sunny place for shady people".

Charlene met Albert in 2000, when competing in a swimming event in Monaco and has been by his side since 2006, when she accompanied him to the opening ceremony of the Winter Olympics. They got engaged last year.

A commoner marrying into the Grimaldi set is nothing new, after Albert's mother, Princess Grace – who was at least Hollywood royalty, if not the European variety – married Prince Rainier in 1956.

But unlike her long-dead mother-in-law, various portraits have described Charlene as being lonely in Monte Carlo, unable to master French and with no official job beyond appearing at her fiancé's side. She has also struggled to master European royalty's enduring insistence that aspiring female members of the clan must be seen and not heard. During an interview with the French journalist Patrick Poivre d'Arvor, the couple were asked if they wanted children to one day succeed Albert: "Hey, won't he just give us a break," she snapped, leaving Albert to rather more diplomatically insist that, "we have the intention to start a family".

Maybe it is that people like a rogue and, in the same way that Clarence House will have to work hard to maintain the image of the woman that eventually tames Prince Harry, so Miss Wittstock has deprived the chattering classes of one of its favourite topics of conversation.

After all, Albert is a gossip-monger's dream. A string of supermodel girlfriends and appearances in nightclubs is just the start. He is known to have fathered two illegitimate children – in one instance he was forced to 'fess up after DNA tests proved what had previously been denied.

The fact that Albert derives much of his $1bn fortune from the property of the mega-rich and the money they spend in Monaco's casinos, does nothing to diminish his image as a man who enjoys the good times.

He might feel it's time to replace the image with "Albert: family man", but selecting an obscure blonde who seems to lack the charisma or star quality of his mother has yet to prove successful.

Or maybe it is just that Monegasques still mourn Grace, who arrived in Monte Carlo without needing to get used to the glamour.

Despite any lingering misgivings, either on the part of Miss Wittstock or others, the wedding will be a grand affair. As well as the de rigueur celebrity guests, who will fill some of the 3,500 seats in the courtyard of the Royal Palace, where the religious service will be held on Saturday, 7,600 locals will be allowed into the city's old town to witness the wedding first hand.

Chef Alain Ducasse will be serving up a multi-course gala dinner for around 500 guests. Mr Ducasse – who holds an astonishing 19 Michelin stars – hasn't revealed what is on the menu but says it will be local and sustainable. Even some South African wine will be thrown to assuage any homesickness.

The scale of the occasion will be befitting of the Grimaldis. Monaco may be small, but Miss Wittstock is marrying into one of the highest profile royal families in the world. The family, originally from Genoa, has governed Monaco since 1395, and in recent years has actually managed to tighten its grip. A longstanding treaty with France, which would have seen Monaco secede to France in the event of the head of state failing to produce a male heir, was overturned in 2002.

And that leaves an interesting conundrum for royal watchers, who will note that, until the newly crowned princess produces an heir, Monaco could possibly be passed to one of Albert's sisters. The most popular of these – at least until relatively recently – was Princess Caroline. Rainier and Grace's eldest daughter has always shown poise, discretion and a natural flair for regal duties. It didn't hurt that she was seen as a great beauty. But now thrice-married, Caroline, who lost her second husband, the Italian industrial-heir Stefano Casiraghi, in a speedboat accident in 1990, has fought long-running battles with the German press over her privacy since marrying the scandal-attracting Ernst August Prinz von Hanover, the dynastic head of the House of Hanover. She now mostly lives in Germany.

It is Albert's younger sister, Stephanie, who captured the world's attention, when Princess Grace described her as my "wild child".

Stephanie, who in 1982 was in the car crash that killed her mother, set out with hopes of being a pop singer; who can forget (or remember), Irresistible, which reached the top ten in September 1986? In the 1980s, Stephanie lived up to her mother's moniker. After moving to Los Angeles to further her career, she refused to record a thing for five years and then only managed to sell 3,000 copies when she did. Her career in music came to an end after starring in Michael Jackson's Caught In The Middle, after which she became a fashion designer. She also followed her father in marrying outside the European royalist set, when she wed her bodyguard Daniel Ducruet in 1995, before divorcing him a year later. Her second marriage, to Adans Lopez Peres, an Italian circus performer, also failed after just 12 months.

Like another well-known royal that was not adverse to the limelight, Stephanie has, in recent years, thrown herself into charity work, founding her own Aids charity to support people living with HIV and, at the same time, combat the social stigma attached to the disease.

The Grimaldi with the most regal bearing is Charlotte Casiraghi, Caroline's daughter. The stylish 24-year-old has just signed another contract with Gucci to sponsor her horse-riding career, but she doesn't perform any official duties.

It is the multiple marriages, untimely deaths and unusual choices – which, let's be clear, began with Rainier's wooing of Grace Kelly – that have propelled the Grimaldis into the limelight, more than any other monarchy in Europe, save, perhaps, for our own.

Nowhere except Greece does the world really mind about the largely benign Greek royals and that is repeated with the monarchies in Norway, the Netherlands and Belgium. Only Spain's royals come close to the houses of Windsor and Grimaldi for their appearances in glossy magazines and newspapers, but the situation there is different. King Juan Carlos stood up to Falangists after the death of Franco in 1975, and won, ensuring him and his family have become symbols of freedom and democracy, rather than of privilege and wealth.

The British press largely leaves the Grimaldis alone, except at a time of a wedding – we've got our hands full with Harry and his regular difficulties getting in and out of West End taxis in the early hours, but for the equivalent of the red-tops on the continent, the Grimaldis of Monaco are fair game. If Charlene Wittstock didn't know that before her alleged dash to Nice airport, she would have when she got back: "Albert and Charlene, a marriage in danger," screamed the headline of the L'Express website, which was followed by a breathless description of the race to the airport.

"Charlene Wittstock had learned a few hours earlier that the private life of the man she was about to marry, who publicly acknowledged in 2005 a child from an adulterous relationship, was not as exemplary as she had imagined," it went on.

After the wedding, Princess Charlene – as she will become known – will get to go back to South Africa, on honeymoon, with her new husband in tow. But, by then of course, she will be a Grimaldi.

The bolters: Runaway brides

By Gillian Orr

Julia Roberts and Kiefer Sutherland

The Hollywood couple were engaged in 1990 after meeting on the set of Flatliners. A studio-paid-for wedding was set for June 1991, but Roberts broke things off just three days before the ceremony. She then disappeared to Ireland to be with Jason Patric, Sutherland's Lost Boys co-star and good friend. The actress famously went on to star in a 1999 rom-com called, er, Runaway Bride.

Crystal Harris and Hugh Hefner

When the 25-year-old model called off her engagement to the Playboy octogenarian earlier this month, Hefner tweeted: "The wedding is off. Crystal has had a change of heart." July's Playboy cover featuring Hefner's bride-to-be and the words "Introducing Mrs Crystal Hefner" were updated with a sticker reading "Runaway Bride In This Issue".

Jennifer Lopez and Ben Affleck

The movie couple formerly known as "Bennifer" met on the set of megaflop Gigli and became engaged in 2002 after Affleck reportedly proposed with a diamond ring worth more than $1.2m (£740,000). They postponed their California wedding just four days before they were due to walk up the aisle, blaming the excessive media attention surrounding the event.

Katie Holmes and Chris Klein

This all-American couple had been together for five years when Holmes broke up with the American Pie star in 2005. It was only two months later that Tom Cruise was jumping up and down on Oprah's sofa, announcing his love for the erstwhile Dawson's Creek actress.

Rose McGowan and Marilyn Manson

The Charmed star was in a high-profile relationship with shock-rocker Marilyn Manson, but called off their two-year engagement in 2001 over "lifestyle differences". It wasn't the first time that McGowan was to get cold feet – she ended her engagement to Sin City director Robert Rodriguez in 2009.