One thing is clear – Prince William’s decision to spend the next five years as a full-time RAF helicopter search and rescue pilot means that he and Kate Middleton will either marry soon, or not marry at all.

Incredibly, even those who are whisper-close to the future king were admitting this week they have ‘no idea which way it will go’.

One confessed that William’s future with Kate is ‘one topic he never discusses’.

Taking to the floor: Kate Middleton falls flat on her back at a charity roller disco in south London

This was not to say, they cautioned, that he didn’t ‘love’ her. They think he does.

But the question is this: is William’s chronic fear of being locked into the straitjacket of royal ribbon-cutting too soon so great that he is prepared to risk the relationship to avoid it?

His decision  –  and according to aides, it was his decision alone  –  inevitably means lengthy periods of weeks and even months when he and Kate will be hundreds of miles apart.

Kate’s friends, at least, are not surprised that her response this week  –  as the British economy shook  –  was to be pictured in disco sequins and tiny shorts and capering about in roller skates, laughingly falling over with her long legs stretched out on the dance floor. The message was clear: ignore me at your peril.

Whether she was wise to disport herself in this inelegant manner is another matter.

Decision time: Prince William’s decision to spend the next five years as a full-time RAF helicopter pilot means that he and Kate Middleton will either marry soon, or not marry at all

The Queen, it must be said, already thinks that Kate is ‘something of a show-off’, and Buckingham Palace courtiers were ‘appalled’ at what they saw as a ‘most unladylike display’ at the roller skate charity evening.

Never have the pitfalls of being a royal girlfriend been more cruelly exposed.

‘What do they want her to do  –  sit at home every evening watching television just because her prince is away?’ complained one of her oldest chums yesterday.

‘Kate’s in an impossible position. She’s hates that awful phrase “Waity Katy” and it makes her mother quite upset. It’s why she’s asked all her friends to call her “Catherine”.’

Cynics are already suggesting that William’s decision, at the age of 26, to become a regular in the RAF  –  which will take him away for long periods of time  –  is, at the very least, convenient in terms of his relationship with Kate.

Also, something of a peacock, he is said to be ‘in love’ with the RAF dress uniform.

‘His decision provides her with the perfect opportunity to walk away  –  if she wishes,’ one says. ‘He’s going to be tied up, probably in some Northern coastal station or even in Scotland, while she’s in London.’

Of course, there is no reason why a young RAF officer shouldn’t share a home with his wife in married quarters. The Queen herself lived briefly in Malta with Prince Philip after they married in 1947, when he was a serving officer in the Royal Navy.

What the future holds: Prince William is supported by Kate Middleton at his graduation from RAF Cranwell earlier this year

But when something similar was attempted by the Duke and Duchess of York while he was a Royal Navy helicopter pilot, it didn’t work out as they hoped.

They rented a house in Dorset near where he was based, but never spent a night there. Instead, he remained on the naval base while she languished in Andrew’s Buckingham Palace apartment. Little wonder it wasn’t long before the marriage was in trouble.

Kate’s friends say she is not only better equipped than Fergie for life in RAF married quarters but is prepared to live in them as William’s wife.

‘If she has to wait for him, she will,’ one says knowingly.

‘They have split up before, remember, and William has always come grovelling back on her terms.’

The fact is, however, that without any defined role or any proper guidance from Clarence House of what is expected of her while he is away, Kate is left to make her own decisions about how to fill her days, which are scarcely arduous.

Her ‘job’, remember, is helping compile and edit catalogues for her parents on-line party accessory company, Party Pieces.

Meanwhile, one woman said to be ‘ dismayed’ by this week’s turn of events is the Duchess of Cornwall. Camilla, 61, is famously lazy and her official diary has far more empty pages than most other members of the Royal Family.

Extra work: Duchess of Cornwall, Camilla, may have to do more royal duties, with Prince William in the RAF until he is 31

With William in the RAF at least until he is 31, and therefore unable to be an active full-time royal, it means that it will be another five years before he (possibly with Kate, of course) is available to share the onerous burdens of official royal duties.

‘There’s little doubt that with William off the scene, the Duchess will just have to do more – and she’s not going to like that,’ says one of her circle.

‘She hoped that with William’s arrival on a full-time basis, she and Charles would be able to step back a little and relax more.’

Ironically, that is not how the Prince of Wales sees it. In November he will be 60, and Charles views the extended absence from the regular royal scene of his elder son and his highly photogenic girlfriend as an excellent opportunity for himself to occupy the spotlight at least until he is 65.

‘Remember how put out he was when he’d just married Diana and she was getting all the attention?’ says a senior Palace adviser.

‘Well, he hasn’t changed in that respect very much at all. And everyone knows that if William was a full-time royal, he would instantly take over as its star, especially as he’s so like his mother.’

For Charles, though, there is a new item on his personal agenda. As he sees it, the longer he can retain the public spotlight, the less is he likely to meet resistance to fulfil his ambition to make Camilla his queen when he ascends the throne.

Only last week it emerged that he has been holding meetings with Constitutional experts and religious leaders to impress upon them his desire and determination that Camilla should not be merely his ‘Princess Consort’  –  as Palace advisers said she would be at the time of their wedding  –  but Queen at his side.

As for Kate Middleton, uncertainty concerning her position has even spread to the Royal Protection Squad who cannot look after her when she is not with William because she remains simply his girlfriend, and fear they will ‘get it in the neck’ if anything untoward were to happen.

But they do now watch over her when she is with the Prince. For example, two weeks ago an experienced officer was attached to her when she and William flew to Salzburg in Austria for the wedding of the sister of a friend from their St Andrews University days.

But when they got home, she was alone again as William returned to his military duties and the protection officer also disappeared.

The truth is that Kate will be 27 in January and in the three years since leaving St Andrews where she and William first lived together, she has done little to establish herself in a career. Perhaps, with William away in the RAF, she will at last get a proper job.