It's official. Top people are now wearing pink

Metropolitan magenta came of age last week, but what were the US presidential candidates' wives saying when they chose the same hue?

Power shade: Lady Gaga, middle - and last week's outfit clash at the debate (Getty Images; Reuters)

Tomorrow in Boca Raton, Florida, when President Barack Obama and Mitt Romney go head to head in the third US presidential debate, you can bet your bottom dollar that Michelle Obama and Ann Romney won't trip up as they did at the second debate on Tuesday, wearing outfits in almost identical shocking pink, like best friends at a junior prom. The colours were so close that even Barbie wouldn't get her pink Cadillac through the gap.

On a Pantone colour chart, that screaming tone is called pure magenta. Magenta sounds dignified, but to most of us it has always been called shocking, bubble-gum, or, unkindly, Pepto-pink. Ann Romney's bright silk $1,690 Oscar de la Renta dress and Michelle Obama's Michael Kors two-piece, a wincing $3,000-plus, set all the news outlets and tweetdecks clacking, from the Daily Mail to the Huffington Post.

Psychologists call pink a happy colour. But it didn't look that way on Tuesday. It seemed like a jaw-dropping mistake; the sort that makes women at a party dash for the exit. But it's clear that something more important happened than two rival wives turning up in the same near-as-dammit dress.

What happened was that a hybrid colour, a mix of red and white, that for the past 50 years has languished on little girls' party dresses, marabou feather trim, My Little Pony, chavvy icing on fairy cakes, cheap pink mobiles, and the frocks of attention-seekers from Barbara Cartland to style-bunny Nicki Minaj, suddenly, just like that … grew up. Two things made this happen. The first is that the presidential candidates' wives did not, in fact, make a fluff-brained mistake. No, they each decided to wear shocking pink in an irreproachable display of multi-tasking. October is breast cancer awareness month. So, instead of just pinning on a bright pink crossed-over ribbon, the symbol now recognised worldwide, Ann and Michelle went for total immersion. Thus, at the same time as loyally backing their husbands' campaigns in high-visibility, almost fluorescent outfits, they turned themselves neatly into walking billboards for their cause.

While cynics might interpret the outfits as a shrewd political move, it actually looks like a sincere one as well. For Ann Romney has survived breast cancer, and Michelle Obama espouses many worthwhile causes besides her husband. In the month dedicated to breast cancer awareness, only an idiot would pass up the chance of manipulating the stage at a national rally by turning up in lime green. The second reason is that shocking pink has been getting a sorely needed psychological makeover for some time, which change has built to critical mass this year.

We accept that colour, combined with other aspects of our clothing, conveys meaning, intentionally or subliminally. But, since the 1930s, pink has been the Jekyll and Hyde of the colour world, its psychological meaning hard to grasp. This is because of its uncomfortable seat on the spectrum, half way between red and white. We understand and often admire sophisticated, sexy, adult, assured, sometimes dirty, sometimes naughty, red. We respect virginal, youthful, serene, innocent, naïve, clean, white. But mix them together and what message are you sending?

An example of red's clarion force is Ann Romney's appearance at the Republican National Convention in August, to give her first solo speech in support of Mitt's second presidential nomination. Before she took to the stage in Tampa, a CBS news poll said that Mitt was suffering from an "empathy gap" with voters, a gap Obama was no slouch at driving a truck through. Then, Ann went on, in a shimmering silk dress of clear cardinal red. The silk glowed like fire, and Mrs Romney's effulgent figure fixed the audience's attention on her, while her words boosted her husband's candidacy.

But unlike red, pink's numerous incarnations are visually very different. Its appearance and emotional temperature range strikingly, from delicate, palest cherry blossom to strident gobstopper. And because of that, this mongrel hue has collected an army of aficionados, connotations and oddities, from baby bootees to pink-crazed, mainly female, children and junior ballet-dancers to boa-wearing drag queens; to gays and the pink pound; to 2012 Olympics transport volunteers, Surrealist fashion designers, exhibitionist singers, eccentric old ladies, and poodles.

In recent history, the unhappy beginning of what has become pink's adoption by gay men and women can be traced back to the Second World War. Nazis used a pink, inverted cloth triangle stitched on prison uniforms to identify homosexuals in prison camps (in a similar way that two yellow triangles were overlapped into a star, to identify Jews). Turned to point upwards, in a positive direction, the pink triangle has long been reclaimed as a badge of pride, as well as both the symbol and the actual badge of gay pride. The colour has also gained a gay identity through being the advertising pages (the pink pages) of the influential LGBT magazine, The Advocate, first published in 1967.

Shocking pink's connotations of punky affront and decadence are currently well-exploited by Lady Gaga, by rapper Nicki Minaj in her various Barbie-esque permutations, and by singer-songwriter Alecia Beth Moore, who goes by the stage-name P!nk. Yet, 1930s fashion designer Elsa Schiaparelli had done most of it decades before. Schiaparelli designed Surrealist clothes, some in collaboration with Salvador Dali. One dress represented slashed and torn flesh, a forerunner of Gaga's raw-meat dress. However, Schiaparelli is most famous for putting the word "shocking" into pink. Launched in 1937, her first perfume, Shocking, was sold in a glass bottle shaped like a female torso, and packaged in what came to be known as shocking pink. It was intended to disturb, and it did. Women who wore either the colour or the perfume felt avant garde; unsafe, unsettled and very sophisticated.

In recognition of that, in New York this May, the Metropolitan Museum of Art's Institute of Costume held an exhibition on Schiaparelli and Prada. Then, September's US Vogue, the most important edition of the year, carried photographs of Schiaparelli's dresses. Celebrities such as Julianne Hough turned up to the Met's launch party in sexy, shocking pink evening dresses.

Meanwhile in London, with much less glamour, the Olympics adopted shocking pink, now officially called magenta by the delivery board, as the colour-ident of the capital's transport system, including all Olympics signage on the Tube. Thousands of volunteers appeared wearing lurid deep pink and purple anoraks, an unfailingly unflattering garment for anyone of either sex, but one that was certainly neither childish, nor outrageous.

So, as Michelle and Ann stepped out to back their husbands they did so wearing a newly grown-up colour. No longer "girly" but rehabilitated as Olympian, egalitarian, compassionate. These women were not opponents wearing Barbie pink, humiliated by cruel coincidence; but two strategists and campaigners, united by intelligence, wearing metropolitan magenta.

Philippa Stockley is a clothing historian, novelist and painter