The Monegasque succession: The prince, his son and a deep silence in Monaco

News of the latest addition to the ruling family of one of Europe's smallest states has been greeted not with a 21-gun salute but with a terse 'no comment' by the palace spokesman. But as John Lichfield reports, irregular heirs are nothing new in the Grimaldi dynasty

Of all the rumours which have clung for years to the enigmatic figure of Prince Albert of Monaco, one, it seems, can finally be discounted. His Most Serene Highness, Albert II, is not gay.

The magazine Paris Match yesterday carried 10 pages and six photographs of the Prince and a little boy, with a lengthy interview, which chronicled, convincingly, the existence of the Prince's 19-month-old Alexandre. The little boy is the son of Albert's former girlfriend, Nicole Coste, 33 and born in Togo, who worked as an Air France air hostess.

The pictures of a grinning Prince Albert, 47, playing with, and feeding the child, the exhaustive details in the interview and the "no comment" from the Royal Palace, leave little room for doubt that the story is true.

Similar interviews and "family" snaps were sold to German and Italian gossip magazines. The details of the Paris Match "scoop" were sold in advance to the Daily Mail.

Two obvious questions arise. Why did Mme Coste choose to reveal, at this time, the existence of Monaco's hidden "black prince"? In her interview with Paris Match , she says elaborate efforts were made to hide the boy from his grandfather, Prince Rainier, who died last month.

Now Prince Albert has become monarch of the caviar-crumb state beside the Mediterranean, Mme Coste presumably believes that he will have a freer hand to recognise the boy publicly. She says in her press interviews that he has already provided for them financially, including a flat in a wealthy area of Paris and a villa near Monaco in the south of France.

But she admits that she wanted her son - her third son - to avoid the fate of President François Mitterrand's illegitimate daughter, Mazarine, who spent her childhood in a twilight world of state secrecy.

Mme Coste says she has no financial or dynastic ambitions: she just wants her son to grow up to know that his father has publicly acknowledged him. It can also be reliably assumed that Mme Coste and Alexandre have earned a great many euros from drawing the attention of the world's media to their existence.

Is there any chance of Prince Albert recognising the boy as his heir? He has, Mme Coste says, already signed a document which formally recognises the little boy as his son. The Monaco royal line is punctuated with illegitimate children who eventually became royal princes and princesses, including Prince Rainier's mother, Princess Charlotte, who was the daughter of an Algerian maid.

But in this case, quite apart from inevitable suspicions of institutional racism and resistance to a mixed-blood prince, it seems unlikely that Alexandre Coste will ever become Prince Alexandre Grimaldi.

The Royal Palace, more used to dealing with stories about the romantic escapades of Prince Rainier's daughters, Caroline and Stephanie, than the secretive private life of Prince Albert, has issued a terse, unequivocal non-statement: "There will be no comment, not today, not tomorrow, not in a month." A lawyer said: "A judicial strategy will be determined."

Previous illegitimate sons and daughters of princes of Monaco became part of Europe's oldest royal family because there was little choice. There were no other heirs and the illegitimate offspring were needed to preserve the dynasty. This is no longer the case.

The law of succession in Monaco was changed three years ago, precisely because Prince Albert showed no signs of marrying and producing children. The crown now passes to his sisters and their children, if he dies without producing a legitimate son or daughter.

In other words, the political impact of this week's revelations on the tiny state on the French Riviera coast (marginally larger than Hyde Park and Kensington Gardens) is likely to be negligible. The 6,000 Monegasques and 26,000 other residents will shrug their shoulders, as they have so often in the past, and blame "the media" for reporting the existence of Alexandre, rather than Prince Albert for producing him.

But there will be renewed questions about the judgement of Prince Albert, who was never quite trusted by his father to take a serious role in running the principality, which is, in effect, the family business.

The Prince appears to have behaved, on the whole, honourably towards mother and son. But if wanted to keep them secret, why did he allow Mme Coste to take the "family snaps" of him cuddling and feeding the boy? Every experience of the detailed love lives of his sisters might have suggested that such pictures were bound to appear in Paris Match, or a similar publication, sooner or later. Mme Coste, who has two sons from a previous marriage, told Paris Match that she met the Prince while working as a hostess on a Nice-to-Paris flight, on 13 July 1997. He took her mobile telephone number. They became lovers. They were seen in public together. Mme Coste even accompanied Prince Albert to an official reception at the Royal Palace, where she briefly met Prince Rainier.

This, she said, was the beginning of the end of their affair. Prince Rainier called Albert aside after the meeting. Two hours later, she said, he emerged to tell her that they should "perhaps only be friends".

The relationship cooled but they made love at least one more time. Alexandre was conceived, she told Paris Match, because she had forgotten to take one of her contraceptive pills.

At first, Prince Albert, part of an ostentatiously Catholic royal family, insisted she must keep the child, she said. Later, he changed his mind and tried to persuade her, through a lawyer, to have an abortion. By this time, she was three months' pregnant and a legal abortion was no longer possible in France.

"For the first five years, I used to go to Monaco about once a month," she told Paris Match. "Over the months, I fell very much in love ... He didn't tell me how he felt but I could feel the way his heart was beating ... There are signs that you cannot mistake when you are in someone else's arms ... He told friends that he liked my maternal side. I found him very moving."

After her meeting with Prince Rainier, about three years ago, their encounters became less frequent, she said.

When she confirmed that she was pregnant, she said Prince Albert told her: "Keep it. I will look after everything. You will never want for anything. I don't promise to marry you but keep it and don't worry."

Three months later, Albert's lawyer signalled that he had changed his mind, she said. "His lawyer said, 'Do you realise that, if it's a boy, it will be used against him to prevent Albert from becoming monarch, because the boy could claim to be his successor'?" For a period, Prince Albert refused to see her, she said. When the boy was two-and-a-half months old, he visited them for the first time, she said. "I asked if he felt anything. He said he didn't know yet. I wanted Albert's father [Prince Rainier] to know his grandson. I sent him a word and picture of Alexandre. I had been told he knew all about it. My note was blocked by the lawyers. In fact, Rainier knew nothing ...

"I just wanted Alexandre to be recognised. I didn't want him to have to grow up like Mazarine. I didn't imagine for a second that he could ever be a potential heir."

DNA tests on Albert and the boy proved his paternity, she said. There is also a startling resemblance between Prince Albert and alleged son in the published photographs.

On 15 December 2003, Mme Coste said, she met Albert and his lawyer in the offices of a notary. "Albert signed an act of recognition. He did it it out of respect for me, on the understanding that nothing could be formally proclaimed until his father had died.

"I was given no piece of paper, just the registration number of his declaration. I asked for a formal declaration from the notary on several occasions. I was always told, 'Later'.

"After Rainier's death, I asked the notary again for Albert's promise to be kept and that his recognition of paternity should be entered into [Alexandre's] official family record. The notary said, once again, that it would have to wait. 'Prince Charles waited 37 years to marry the woman he loved', I was told."

Albert began nonetheless, to make regular visits to the boy, she said, most recently in February this year. Mme Coste told Paris Match that she suggested to Prince Albert that their romance could resume but he refused, saying he feared she would have another child.

"When he visits, he is very at his ease," she said. "I cook. The last time ... Albert was in the next room with his son. The child had a little fall. 'I don't know what to do. I'm not ready for this', Albert said, obviously upset.

"I said that Alexandre would expect him to look after him. He went fetch a piece of ice and lotion. He changed his nappy. He fed him. Then he went on to another meeting." Since February, she said, with Prince Rainier's final illness and the accession to the throne of Albert, she has heard nothing.

Mme Coste said she had decided to reveal her story to the press so Alexandre could "grow up normally with a father". She added: "I want the lies to end. I can no longer lie, hide myself, pose as the mistress of one of his friends. I have lost my identity and live in a state of near illegality. I am scared for my son's mental balance.

"More and more rumours are circulating and I want the truth to be known so that his two older brothers can respect their mother." Asked whether she feared that Albert might reject her and the child after this week's revelations, she said: "No. I think that Albert is a very correct man who finds himself a bit lost in all of this. I would like to appeal to his heart and I think he will understand what is in his son's best interests. I just want him to face up to his responsibilities.

"I am not a gold-digger. No one would begrudge him having had a love affair which produced a beautiful child."