Key Points:

Our First Lady, Bronagh Key, is an attractive woman. Yet the self-confessed "tomboy" could become a fashion trendsetter for Kiwi women with the right wardrobe, comparable to Princess Diana and Jackie Onassis, according to leading New Zealand fashionistas.

Within weeks of John Key and the National Party taking office, the mother-of-two has committed what some say is a serious style blunder by wearing the same outfit twice.

Bronagh sported a purple Adrienne Winkelmann jacket as her husband was sworn in as Prime Minister in Parliament last week, the same outfit she wore at the party campaign launch - a first lady faux pas.

She was able to keep a low profile when Key was an opposition MP. But as the wife of the Prime Minister she can no longer avoid the limelight.

In a recent Herald on Sunday interview, Bronagh said she took little notice of the wives of other politicians like Carla Bruni-Sarkozy, Laura Bush, Cindi McCain, Hillary Clinton and Michelle Obama.

Obama sashayed on to the world stage with a swish black and red Narciso Rodriguez dress during Barack's victory speech a fortnight ago, while Clinton donned an Oscar de la Renta evening gown in the White House for a spread in Vogue.

Bruni-Sarkozy went a step further to become the only first lady to pose nude for a photo shoot.

And while most people would baulk at the idea of Bronagh following suit, she would benefit from ditching the power suit to adopt a more feminine look, say top designers.

Her style was "safe and a bit frumpy", said Hawke's Bay-based Kirsha Whitcher, designer of Salasai.

"She's an attractive woman with a good figure, she could definitely be more adventurous with her clothes.

"We would accentuate her legs and waist, changing her tomboy look into a slightly more feminine and sexy version," she said.

Whitcher also plumped for slightly darker hair, cut in a bob, topped with a plum lipstick for a confident look.

Auckland-based designer Angela Lewis went further.

"Definitely no power dressing. Take that down to the recycling bin at Parnell Primary.

"Our First Lady will look wonderful in frocks, frocks, frocks and frocks that rock. She is a delightful woman with gorgeous colouring and appears to have a defined sense of herself."

For day wear, Yvonne Bennetti recommended a silk trench coat - black or bright jewel - with cotton satin pants and a lilac silk, chiffon blouse underneath.

"For an evening event, a black one-shoulder full-length dress with a diamond belt," she said. "A silk chiffon dress would be perfect during the day.

"I'm thinking a bow dress in amethyst, a classic French style but the colour makes it modern."

With a slim frame, and hair full of "shine and bounce", Bronagh could become a fashion icon in New Zealand with the right wardrobe, said Theresa Brady, designer for Sable and Minx.

"To really stand out is about making clothes your identity.

"Princess Diana didn't look like a fashion icon when she was a kindergarten teacher, she grew into it.

"Bronagh, of course, has the ability. She's an attractive woman.

"Not everyone would want to be in her position but you'd have to embrace it."

Brady can see shades of Jackie Onassis - the wife of assassinated US president John F Kennedy - in Bronagh, particularly dressed in well-cut satin capri pants, or a simple silk tunic, with a lightweight summer trench coat teamed with flat shoes.

"A quick change for an early evening outdoor event into a classic but fashionable Jackie O dress with a slimmer box jacket and a pretty scarf waist tie and comfortable but killer heels.

"And maybe her husband could commission a silver fern diamond brooch, to adorn her evening dress on her maiden voyage to the Palace. "He could also give one to the Queen - he is loaded after all," she said.