Kate Middleton was outshone by New York heroine Chirlane McCray. Source: Getty Images

But for once, another woman is upstaging her.

This is Chirlane McCray, Mayor Bill de Blasio’s wife and the darling of the Big Apple.

The city has gone wild for Ms McCray, a black activist and former lesbian whose liberal image make her the perfect emblem for the cultural capital.

The Duchess of Cambridge, right, and Mayor Bill de Blasio's wife greet guests at Northside Center for Child Development. Source: Getty Images

The mayor’s wife was praised for her “coat game” — usually Kate’s department. Source: Getty Images

She and the mayor have been compared with power couple Bill and Hillary Clinton.

Ms McCray is far more outspoken than quiet Kate. De Blasio has repeatedly called his wife his closest adviser, and she played a major role in his election campaign.

“You could say that I am Bill’s conscience, confidant or adviser, but none of those words are exactly right,” Ms McCray told AP in an email interview. “We are partners in love and work.

“There is only one Mayor, but when he needs help I’m there for him, and vice versa.”

The city’s first lady met Kate Middleton in Harlem, while Prince William headed to Washington.

Ms McCray wore a raspberry Nanette Lepore coat, recycled from her husband’s swearing-in ceremony in January, and a blue blazer once indoors.

Kate, who is five months pregnant, cut a more sombre figure in a black coat with white trim as the pair greeted children at a children’s development centre.

Ms McCray and the Duchess have both made mental health a key issue, but the 59-year-old former activist and speechwriter is by far the more outspoken. Source: AFP

New York’s first lady is seen as a real “woman of the people”. Source: AFP

The attention on the mayor’s 60-year-old wife was perhaps even greater than the hype surrounding 32-year-old Kate.

The media has already observed that the royal visit “put NYC’s powerful first lady on the world stage” and that Ms McCray had “superior coat game”.

It was reminiscent of a pre-Thanksgiving trip to a Brooklyn hair salon last month when Senator Kirsten Gillibrand went virtually unrecognised and the first lady was greeted like a rock star.

Ms McCray posted an article about her tour of the Northside Center with Kate on her interactive multimedia blog #FLONYC, inspired by Eleanor Roosevelt’s My Day.

She noted that the Duchess had “made mental health one of her signature issues”. For Ms McCray, the subject is closer to home. Her daughter, Chiara, opened up about her depression and substance abuse last Christmas Eve.

Ms McCray and actress Teri Hatcher during the UN commemoration of the International Day For The Elimination Of Violence Against Women. Source: Getty Images

Former lesbian Ms McCray is Mayor De Blasio’s closest adviser. Source: AP

“I don’t know anyone who has not been affected personally or by a family member, friend, colleague or neighbour,” said Ms McCray. “And yet society still portrays mental illness as a rare and shocking secret. As a result, far too many of our neighbours are suffering in silence.”

New York’s first lady, who is seven years older than her husband, is known for being a woman of the people.

She was open about her excitement about meeting Kate, confessing: “Never in my wildest, most far-out dreams did I ever think I’d be spending time with the Duchess of Cambridge.”

Ms McCray is a former activist poet who was working as a speechwriter for Mayor David Dinkins and identified as a lesbian until she met De Blasio.

They raised their two children in a middle-class Brooklyn neighbourhood, and the move to Gracie Mansion does not seem to have changed the family.

“She doesn’t carry herself like royalty, she carries herself like a regular person,” said Christina Greer, a political science professor at Fordham University. “A lot of New Yorkers think ‘If anyone in politics can really understand me, it’s her.’”

The couple mark the Martin Luther King Jr. holiday by preparing meals with Girl Scouts. Source: AP

The couple, pictured at Mayor De Blasio’s swearing-in, have been compared to Bill and Hillary Clinton. Source: AP

She is admired for her openness and honesty. But her outspoken persona has also been used against her, with a New York Post headline screaming “I was a bad mom!” after she confessed to at first struggling with motherhood.

Another Post front page claimed Ms McCray didn’t trust Police Commissioner William Bratton, which City Hall denied.

“We were the focus of some blatant lies, and we had an obligation to set the record straight,” said Ms McCray.

She was also criticised after her chief-of-staff, Rachel Noerdlinger, was found to have omitted from her background check the fact that she was living with a boyfriend who had pleaded guilty to manslaughter and insulted police on his Facebook page.

Ms Noerdlinger eventually took a leave of absence.

“McCray has become a target of sorts,” said George Arzt, a political consultant and former press secretary to Mayor Ed Koch. “Some people are uneasy about a person who was not elected appearing to have so much power.”

But the royal tour will only make Ms McCray an even more recognisable figure on the world stage.