The Yorks at Bea’s birthday bash.

It was probably the social engagement of the year so far: Princess Beatrice’s 18th birthday party at Windsor Castle hosted by her parents, the Duke and Duchess of York.

A lot of guests dropped out at the last minute, however, including the Queen and Prince Philip, the Prince of Wales and the Duchess of Cornwall, and Princes William and Harry, who were on duty with the Army.

The Queen’s omission was surprising since she invited the £400,000 party to be held at her principal home, Windsor Castle. A senior royal source said: “The Queen has had a re-think. She doesn’t think it right for a couple of old fogies to be at a party with loads of teenagers. She thinks she’s too old to boogie the night away.”

However, Princess Beatrice chose to celebrate her 18th birthday in style, with guests wearing a variety of period costumes to tie in with the theme of the evening — 1888. The popular Bea, her sister Princess Eugenie, 16, and their parents the Duke and Duchess of York all joined in the event, with Beatrice wearing a blue and gold gown by British couture label Marchesa (pictured).

I’ve no doubt a good time was had by all.

The Duchess of York is set to make her first official Royal appearance for 14 years when she attends the Order of the Garter service at Windsor in a fortnight. Fergie will also attend the private family tea that will be held after the ceremony.

But the biggest sign of her rehabilitation into the Royal fold will come when she co-hosts daughter Princess Beatrice’s 18th birthday party at Windsor Castle on July 15.

For Beatrice this is more important than the event itself. It’s the best gift the Queen could have given her. The Monarch is using the occasion to mark the return of her former daughter-in-law, the often-exasperating Sarah Ferguson, back into Royal favour. Why, we may ask?

The UK Mail On Sunday reports: “On the face of it, the rapprochement is an astonishing about-turn for the Palace, which has steadfastly refused to acknowledge Fergie, mainly at the behest of Prince Philip who hasn’t uttered a single word to her in ten years. In truth, it is the culmination of many years of behind-the-scenes lobbying by Beatrice to have her beloved mother once again in favour.”

Princess Beatrice was born at 8.18pm on August 8 (8/8), 1988 — the most auspicious date of the past century, according to the Chinese calendar. She is, by many accounts, a genuinely helpful, good-natured girl. Her election as Head Girl of her Ascot School demonstrated how popular she is with her peers, despite a long battle with dyslexia.

The party promises to be the most lavish since Prince William’s 21st birthday celebrations three years ago. This time, the dress code will be 18th century, reflecting the many “8s” associated with her birth.

The Queen rarely gives parties on such a grand scale and the fact that she has done so for Beatrice is a sign of her affection for the young granddaughter who calls her “Granny One”.

The Queen has also instructed 16 senior Buckingham Palace aides to help the young Princess adjust to public life. No expense is spared for Bea, who is 5th in line for the Throne.

The centrepiece of the bash will be a splendid Georgian banquet prepared by the Queen’s own chefs. The music will be supplied by a string quartet, while the historic Waterloo Chamber will be filled with the scent of English roses.

Prince William and Prince Harry, together with the Duke of Edinburgh, will be among the 400 guests who will transform themselves for the night into 18th-century characters from Mozart to Marie Antoinette. It’s widely agreed that Beatrice’s birthday party is set to be the social event of the summer.

Princess Beatrice (left) with her father and sister.

Popular Princess Beatrice is having her 18th birthday party a month early because most of the Royal family will be in Scotland when the day in August actually falls.

True to many similar Royal parties, the bash will have a theme. How very Fergie-like then that the masked ball for 200 will require guests to display “bustles and corsets”.

The choice is built around Bea’s birth date of 08 (August), 1988, so the 1888 theme seems like a good idea.

At least Prince Harry won’t be able to turn up in a Nazi uniform. What he does wear though, might be equally embarrassing.

See also: Duchess and Daughters Watch DVDs for 20 Hours on Aristocracy Anecdotes.

Finally, it’s over. The errant boyfriend, American Paolo Liuzzo, 24, has been dumped by a shattered Princess Beatrice, 17.

The story so far: Liuzzo received three years probation after a nightclub brawl which ended in a death. He was lucky that the original manslaughter charge was reduced to assault. Now the New York socialite has been taken back to court after breaching the order by going on a skiing holiday with Beatrice and the Duke and Duchess of York. Reports suggested he faced a two-and-a-half-year jail sentence.

He walked free last week, as a judge in Massachusetts lengthened his probation by a further six months. Judge John McCann warned him, though: “There is always the possibility of incarceration in the future if there is a further violation.”

Liuzzo’s attorney said: “He is shocked, but relieved he is not going to jail. He will abide by all his restrictions.”

Now he’s been dumped by his shaken teenage girlfriend. Perhaps in future, Beatrice’s mother, Sarah, Duchess of York, will refrain from taking her daughter to dubious nightclubs “on the pull”?