Obviously it helped that she has no problem forking out £6,000 a week for the get-back-in-shape holiday villa in Phuket, complete with chef turning out low-fat meals, and fitness instructor jetted across the world to her by Sophie Dahl.

And it is also true that she doesn’t look fabulous in quite the same way as before. There is nothing superwaif, heroin-chic, aggressive-smoker or party girl about the woman in these pictures. She is just a beautiful normal-sized person with curves here and there, and a blissed-out smile on her face.

Still, the message to anxious non-celebrity mums comes across loud and clear: “Shed that weight. Paint your toenails. Try harder!” No wonder that many normal women (already so bludgeoned by exhaustion, forgetfulness and pre-dawn wailing that they cannot remember that they have eaten their daily ration of toast and digestives three times over by mid- morning) feel inadequate when faced with these serene paragons of maternal beauty.

It is a hard act to follow when your brain is filled with the fluff of everyday life, the tiring, unglamorous stuff that mothers with dieticians, personal trainers and wall-to-wall nannies don’t ever have to get to grips with. How can you possibly think of going to the gym when first you have to take 39 impossible steps at home — sterilise bottles, find more nappies, remember to put washing in the dryer — and where-are-the-wipes? Anyway, you have no clothes and no one to leave the baby with.

The charity Baby Lifeline is complaining of the unacceptable pressure that makes many young mothers go on dangerous crash diets. To counteract this tyranny, there is even a Campaign for Real Mums in the offing, which will try to get a bit more kitchen sink back into our over-idealised view of motherhood.

Which is all very worthy but, let’s face it, not much fun. As a reasonably new mum myself, the kind of maternal propaganda pictures I still prefer are of Liz Hurley post-parturition, looking glamorous and happy, with bigger breasts than usual and lots of haw-haw headlines about how she must be breast-feeding.

There is no need to show me shots of women shuffling around messy kitchens in dressing-gowns, mumbling about nappies; I know that stuff well enough already, thank you.

I am not convinced, either, by those tearful tales of mothers driven to anorexia by trying to copy Victoria Beckham who, in contravention of every law of nature, seems to get thinner rather than fatter every time she has a baby. Even the quickest of glances through the magazines should be enough to show that most celebrity mums (except Beckham) do not, in reality, bounce effortlessly back into perfect shape as soon as they leave the delivery suite.

There is no such thing as having a baby and staying rake-thin without an effort. Losing weight was hard work for Kate Winslet, who weighed in at 13 stone (82kg) after giving birth and spent months on a tough diet getting rid of her surplus.

Catherine Zeta-Jones joyfully flaunted her more buxom figure for months after her first baby. Sadie Frost, pictured at the weekend with Moss, popped out number four four months ago. Unlike Winslet, she opted not to take off her shapeless grey T-shirt or come out of the shadows. OK, many celebrity mothers do better than civilian mothers at getting back into shape fast for the obvious reasons: they have more money and pampering time. But what really motivates celebrity mothers is fear, because their looks are their livelihood. At least that’s one thing we don’t have to worry about.

Or, as Liz Hurley put it: “My job is to fit into tiny clothes.” She knows that there will never be much work for flabby, sagging former beauties in the tight-clothes department. If celebrities, especially single ones like her, are to provide for their children, their wasp waists will be their best weapon. So it’s no surprise that fear of the future makes some celebrity mothers obsessive about reducing their weight as quickly as possible after giving birth.

You probably won’t ever look that good again yourself. So the only decent thing to do is be pleased that the celebrity mothers are doing it for you, and get all the vicarious enjoyment you can out of their temporary triumph over the ravages of time, cheering them on as they step back into the limelight, flashing their teeth.

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