With the young Royals getting plenty of stick — again — for partying through a recession, another situation is beginning to assert itself.

Prince William and Harry’s “farewell” party at the Whisky Mist nightclub was notable for the absence of Kate Middleton.

The bash was held to see them off before leaving for South Africa to take part in a dangerous 1000-mile motorcycle ride for charity,

Prince Harry and Chelsy Davy were there, as were the now ubiquitous Princesses Beatrice and Eugenie. Even Paris Hilton and Christine Aguilera (pictured) made the effort.

There could be many reasons why Kate didn’t attend, of course, but in the context of recent events, it does seem strange.

The Prince recently decided to spend the next seven years as a helicopter pilot in the RAF’s Search and Rescue unit based in various remote locations. Instead of settling down next year to Royal duties and an intensive period learning how to be King, he surprised both Clarence House and the Palace by his abrupt decision.

Since then, Kate has taken a decidedly back seat, working full-time for her parents’ business, Party Pieces. Her only recent appearance was a rather ungainly performance at a rollerskating charity function she organized herself. A revealing fall drew a lot of unfavourable comments from the press.

Prince William and Kate Middleton in happier times

Has this relationship now run its course? Did William tell Kate, “Let’s see how we feel when I’ve finished with the RAF in 2016.”

In the meantime, perhaps, both are free to go their own ways? Is this a low-key split which will have no announcement and few leaks from insiders?

A lot of people think so, including those of us who have supported this couple through the past three years.

Prince William (pictured, right) and Prince Harry will after all take part in a dangerous 1000-mile charity motorcycle rally through South Africa.

Clarence House confirmed, “The Princes are looking forward to taking part in this arduous motorcycle ride.”

It will be an eight-day ride later this month in an attempt to emulate actor Ewan McGregor and Charley Boorman who rode from John O’Groats to Cape Town in their TV series The Long Way Down.

Now we know the reason Prince Harry attempted and passed his motorbike test after taking an intensive course this summer. It was, it seems, Harry’s idea to raise money for charities, including his own Sentebale, based in Lesotho, and the Nelson Mandela Children’s Fund.

This will not be an easy ride by any stretch of the imagination. The brothers will sleep rough as they cross some of the toughest terrain on the continent.

They will, of course, be accompanies at all times by up to six armed police protection officers.

The ride is being sponsored by Enduro Africa. Each participant will be provided with a Honda CRF 230s, a light 200cc trail bike easy to manoeuvre.

The organizer of the event, Simon Smith, says, “It’s going to be one of the hardest and most demanding things they will ever have done in their lives and at night they are going to struggle to get off their bikes as the pain will be so bad. At times they will be sitting on their bikes looking up at a 60 degree slope wondering how the hell they are going to get up it – not even realizing there is a deep river crossing to get through on the other side.

“It is a very dangerous route and they will undoubtedly collect a fair few bumps and bruises along the way.”

Harry recently returned from training in Canada to be with his girlfriend Chelsy Davy, who needed hospital treatment to remove her wisdom teeth.

William is currently working at the Ministry of Defence, before moving on to the SAS later in the year.

There are more signs of strain between the Royal Family and the Middletons this weekend.

It’s been reported that Princesses Beatrice and Eugenie refused to make space in the front row of a fashion show for Pippa Middleton, Kate’s younger sister. After some embarrassment, she found a seat elsewhere.

It seems that Kate didn’t invite Beatrice to her midnight roller-skating event two weeks ago. Nevertheless, the Princess turned up only to find herself inappropriately dressed.

We also learn that Prince William will be required to spend six years on active service in the RAF following 18 months of training. That adds up to a formidable seven-and-a-half year spell in various inhospitable regions a long way from London.

A chorus of friends and insiders are now claiming that a marriage between William and Kate is off the schedule for at least that length of time.

As Royal Anecdotes suggested immediately after the announcement of William’s decision, a marriage must now be in serious doubt. Extensive preparations by the Palace for a 2009 wedding are said to have been shelved.

As I wrote at the time, all the psychology of this decision fits in with the classic Bolting Bloke Syndrome (our name). He has been with her for so long they’ve become comfortable with each other, but the spark is gone. It’s no longer interesting enough to go the last mile to marriage.

By signing up for a lengthy military service, he creates a wide gap of both time and space between them in the hope the relationship will wither on the vine and fade in the minds of the general public.

The thought may occur that an engagement could still happen at Christmas, as was previously pencilled in, leading to a wedding in the summer. However, would Kate — who enjoys London nightlife — be prepared to live as a service wife in remote parts of Scotland or Wales for seven years, with William out on active duty or standby for much of the time? She would be 35 when he is released.

Again, the psychology says not.

In our view, Prince William has made the decision to move on. It was the only explanation for his announcement, which took everyone at the Palace and Clarence House by surprise.

Kate should move swiftly to shore up her reputation by indicating the relationship is over. Hanging on to an occasional friendship while becoming a laughing stock among her peers, and her gloating enemies, is the worst possible outcome for her.

I believe a wedding was definitely on, and being actively planned for. In the end, William couldn’t bring himself go through with it, but couldn’t end it either. He felt boxed in and made his escape in a helicopter.

Last week Kate was seen out with her first serious boyfriend, a chap who slightly resembles Prince William. He may now be the closest she gets to her Prince.

Clarence House has announced a “star-studded comedy gala to celebrate The Prince of Wales’s 60th birthday.”

I’m not sure how many parties that is now — at least three by my erratic counting.

The press release says it all:

“Comedy greats will help to celebrate The Prince of Wales’s 60th birthday this year with a special one-off comedy show in aid of His Royal Highness’s youth charity The Prince’s Trust.

“The show, called We Are Most Amused, will have a unique line-up with stars such as Rowan Atkinson, John Cleese and Robin Williams on stage together for one night only on Wednesday 12th November.

“The Prince of Wales, who is a keen fan of comedy, will attend the show with his wife The Duchess of Cornwall at the New Wimbledon Theatre.

“Their Royal Highnesses will be treated to a mix of live stand-up and comedy sketches from the world’s greatest comedians to raise money for, and awareness of, the work of The Prince’s Trust which helps to provide opportunities for disadvantaged young people in the UK.

“For the first time in over 25 years, stand-up comedy legend and Hollywood star Robin Williams will perform on a UK stage. Monty Python founder and comic genius John Cleese has promised something extra special in honour of The Prince’s birthday and after a long stint on the small and silver screens, British comedy great Rowan Atkinson will return to the live stage.

“The line-up will bring together the very best in comedy talent – from much-loved established names to fresh young acts from the stand-up circuit – a combination which will appeal to all ages and, above all, to comedy fan and guest of honour The Prince of Wales.

“With further acts to be announced, We Are Most Amused promises to be a night to remember and will be screened on ITV1 shortly after the live event.

“We Are Most Amused will take place on Wednesday 12th November 2008. Tickets will go on sale at 10.30am on Wednesday 1st October and prices range from £25 to £100. To purchase tickets either call 0870 060 6646, go online at www.newwimbledontheatre.co.uk or visit the New Wimbledon Theatre Box Office in person.”

It sounds like great fun, if you like that sort of thing.