Whatever amorous tale they really told, the ostensibly loved-up paparazzi shots that flashed around the world in early January telegraphed the fact that Lily Allen was at last taking her celebrity responsibilities seriously. She was looking unusually svelte, and 20lb lighter than the champagne-swilling drunk who bantered with Sir Elton John during an awards ceremony in September. There she told Sir Elton, mid-slurp, to “f*** off” , disrespectfully reminding him that she was 40 years his junior, “with my career in front of me”.

He amiably replied that, despite his years of sobriety, he could still “snort her under the table”.

But the January photographs showed Lily Allen as never before: in a soft-focus, conventionally glamorous light.

The latest Los Angeles eating fad, the so-called “hypno-diet”, has prompted a marked dive in Allen’s previously prodigious alcohol intake — she’s allegedly been off the sauce since September 22.

Never mind her previous barbs aimed at anorexic models and her vocal support for women with fuller figures, Allen is now on a different page. Shot on a luxury yacht off the chic French Caribbean island of St Barts, the pictures revealed a slender princess of British pop embracing Jay Joplin, the alpha male of Brit art and the multimillionaire owner of the White Cube gallery.

Arriving almost exactly 12 months after the sad miscarriage in January 2008 that ended Allen’s five-month relationship with another man old enough to be her father (38-year-old Ed Simons, one half of the techno duo the Chemical Brothers), the pictures had a teasing piquancy. Was this the beginning of a real romance, or a carefully staged piece of high-profile posturing by a pop star with an important second album imminent, in cahoots with a recently separated art shaker with some unresolved midlife romantic issues?

Joplin, who hasn’t given an interview in eight years, was keeping quiet, not least because, though separated, his marriage to the artist Sam Taylor-Wood has not legally ended. Back in England, and apparently on her own at the end of the first week in January, Allen was also uncharacteristically silent — although she was seen out, and papped, sporting two large rings on her engagement finger.

Guesswork time. Friends report that “a few flings behind closed doors at home” are the only relationships that Allen has engaged in, or wanted, recently. “She’s still not completely got over Ed Simons,” is another regularly heard refrain. According to Simons’s manager, the pair are still quite close.

So was the Joplin clinch, Allen playing the minx — a role that clearly suits — or was she hinting again, as she has in the past, at a precocious desire to give up making music, settle down and lead a quieter life than the chaotic one that has dominated her first 23 years?

Opinions vary on Lily Allen, but on one point her friends tend to agree: she grew up fast. Way too fast, some say.

“She seems at times almost too mature for her age.

She’s like an old soul,” says one of the many fortysomething acquaintances who seem to outnumber buddies of her own age in Allen’s large social circle.

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