Consider the scenario. It was early in the morning and I was heading out to walk the dog. My husband was away on business, so I left my two daughters alone with a girlfriend who'd stayed for the night before. Then, just as she was heading upstairs to the bathroom for a shower, the girls begged to be allowed to join her.

'Sure,' she said, disarmingly, and before I could utter a word, pyjamas, dressing gowns and underwear were shed as all three piled into the cubicle amid lots of excited giggles.

What should I have done? However close your relationship with a friend, I am sure most people would feel slightly uncomfortable and squeamish about encouraging children to get naked with a non-blood relative.

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Jess Spiring (centre) lets her daughters Bibi, 3, left, and Matilda, 5, right, see her naked to make them confident

Natural English reserve, coupled with sensible caution over how these things would sound to others - blurted out in the classroom, for instance - would make most mothers mount those stairs in a flash to intervene.

But not me. I stood back and congratulated myself on a job well done. Seeing how comfortable my daughters, five-year-old Matilda and three-year old Bibi, are with nudity in all its forms - male, female, old, young, fat, thin, in-family and out - makes me proud. I see it as part of my crusade to beat the body issues blighting our children's childhoods.

My philosophy evolved quite naturally. My husband, Reuben, and I often sleep without a stitch, and when the girls started to bound into our bedroom in the mornings, we did nothing to cover up. As they got old enough to tolerate the shower, they would join us there, too.

Occasionally they'd take an interest in Reuben's bits or mine, but we made a conscious effort not to react and to answer their questions honestly. 'When will I get boobies?' Tilda asked. And: 'Oooh, your pompom is funny, Mummy!'

'Um, when you're a teenager,' and, 'Yep, I know,' were my poker-faced replies despite howling inside.

Jess feels that letting her daughters see a variety of naked bodies will teach them that there's no such thing as bodily perfection

As a result, the landscape of our adult anatomy became so commonplace that the girls lost interest. It's not just our bodies they've been exposed to. Matilda can't have been much past three when she saw nudity outside the immediate family. On holiday in Sweden, my mum, the girls and I took a walk beside a lake on a sweltering hot day.

We were all desperate for a swim, but had no swimwear. Mum, having lived there for 13 years after retiring with my father, has adopted the Swedes' much more relaxed attitude and suggested a skinny dip.

Matilda was delighted to examine Grandma's 68-year-old body at close quarters and my art-school-educated mother couldn't have played it cooler.

Similarly, my 40-year-old sister, Jo, didn't flinch one morning when she was showering at our house, where the bathroom doesn't have a lock, and the girls barrelled in to join her. They were less fascinated by her body than her belly button ring.

So it was hardly a huge leap when my close friend agreed to her three-way shower.

I'm not some kind of hippie, free-spirited nudist - I don't even particularly enjoy being naked and grew up in a typically English, covered-up home - but I do believe that seeing real bodies (especially women's) in all their glory will arm my girls with a benchmark to set against the half-starved images on social media that they will no doubt be obsessed with as teenagers.

They will be better able to see the body of whichever Kardashian is flavour of the month as utterly unrealistic, having witnessed, warts-and-all, the naked bodies of real-world women. My theory is already paying dividends. While some mums at school tell me their children have become self-conscious about their bodies, my two have no such hang-ups.

Indeed, they are so body confident, it borders on exhibitionist. After getting hot and bothered tearing about with a classmate on a recent playdate, Matilda thought nothing of peeling off her uniform and undies, much to the bemusement of her friend and his mother, who have coined the term 'doing a Spiring' to mean flashing the flesh.

Covering up and being ashamed of our bodies teaches our girls to do the same

I just wish I had felt like that when I was growing up. I can still recall the agony of being told, at about 11, that my shapeless legs looked like they were on upside-down. In the sixth form, one boy likened my boobs to torpedoes, inspiring the spiteful nickname 'torps'. With very little to compare myself to, I assumed my body was a thing of shame to be covered up.

And that was in a much more innocent time, before fat-shaming on Facebook and the ubiquity of internet porn. Nowadays, we've reached the point where experts are unequivocal about how big an obstacle to a contented childhood body-confidence has become.

A saddening 2013 study found that 47 per cent of 11 to 14-year-old girls admitted opting out of activities such as swimming or performing on stage because of how they felt about their bodies. Another poll found a tragic one-in-five teenagers considered themselves ugly.

It's not just teens who are a concern. In 2011, European researchers discovered one in four seven-year-old girls had tried to lose weight and that girls as young as five were worried about their size.

Would you let your kids shower naked with a family friend? Jess Spiring does. Picture posed by model

A friend recently posted a poignant exchange with her seven-year-old daughter on Facebook, which sharply illustrates the point. 'My gorgeous girl looked in the mirror this evening and said: "I hate my smile, I have a horrid smile." How does this self-esteem issue start so young? Heartbreaking…'

Heartbreaking, yes. But are we too quick to point the finger at social media and popular culture? In truth, aren't we sowing the seeds of self-esteem problems at home?

When we bad-mouth our own bodies, within earshot of our children, especially our daughters, it teaches them to mimic our self-loathing and examine their own beautiful bodies for imperfections.

Covering up and being ashamed of our bodies teaches our girls to do the same. The Swedish approach to nudity means kids there grow up with more of a ho-hum attitude to the human form in all its guises.

Compare, for example, my experiences with Swedish and British swimming pools. At our local London pool everyone is expected to change in private in a cubicle.

In Sweden, it's all open plan, and young, old and even pubescent girls make no effort to conceal their bodies. And before you jump to the conclusion that they're all ravishing size 10 Swedish sirens, they're not.

Over there, there's no need for 'you show me yours and I'll show you mine' games, because I've seen yours so often it's not even interesting any more. This openness sends the subconscious message that there's no need to be ashamed of your lack of thigh gap, or torpedo-shaped boobs, because, hell, no body is perfect.

I'm not suggesting we all start disrobing in the middle of some packed Sunday-morning swim session. But could you stomach a little private nudity? Showering with your children is, to my mind, the least forced and freaky way to make that happen naturally.

You can decide for yourself how far you're willing to go. For me, it's close female friends and, where men are concerned, their dad and my 36-year-old brother Tom. If Bibi and Matilda suggested a shower with my friend's fiance, for example, I'd probably intervene (although to be honest, what's the harm? I've known him for 24 years and would trust him to babysit).