She is the grand-daughter of Caribbean immigrants to America who has just been appointed to a top job by Bill de Blasio, New York's new mayor.
He is the dashing British actor who stars as Sherlock Holmes in the hit television series on both sides of the Atlantic and plays a plantation owner in the Oscar-nominated film 12 Years A Slave.
Despite their very different backgrounds, Stacey Cumberbatch and Benedict Cumberbatch apparently do not just share a distinctively English-sounding surname.
Ms Cumberbatch believes that the star's fifth great-grandfather owned her ancestors on an 18th century sugar plantation on Barbados.
They are "related", not by blood, but by their shared roots in the brutal transatlantic slave trade, she told The New York Times after her appointment as a city commissioner.
Her ancestors were slaves on the island at the time when it was the practice for them to take the family names of plantation owners such as Abraham Cumberbatch.
The star has previously discussed how his name became common among families from the Caribbean because of his forebear's role on the island.
Although there are no paper records to establish the link, it now seems that New York's new chief of administrative services is among them.
Mr Cumberbatch's performance in 12 Years A Slave, which has been nominated for several Oscars, including Best Picture, is not the first time that he has chosen a role that harks back to his family's ties to slavery.
Abraham Cumberbatch, who was born in Bristol in 1726 and died in 1785, came from a family of merchants and adventurers and built the clan's fortune from a sugar plantation on Barbados.
The actor said that it was a "sort of apology" for this history when he played William Pitt the Younger, the abolitionist prime minister, in the 2006 film Amazing Grace about William Wilberforce's fight to eliminate the slave trade in the British empire.
In an interview, he once said that his mother, Wanda Ventham, the actress who also played his mother in the latest season of Sherlock, encouraged him not to use his real name in his professional career because she was concerned that he could face claims from reparations by slaves of descendants.
The Cumberbatch family has faced no such lawsuits. But 14 Caribbean nations last year said they would seek reparations from the former colonial powers of Britain, France and the Netherlands for the slave trade.
The countries have hired the firm of London lawyers that secured compensation from Britain for Kenyans who were tortured under British colonial rule in the 1950s.
The islands have said they will compile an "inventory" of damage suffered and demand an apology and financial damages. Britain abolished the slave trade in 1807 and Tony Blair, the then prime minister, expressed his "deep sorrow" for the practice in 2006.
The Cumberbatches are among many prominent British families who once built their wealth and standing on the slave trade. Researchers said last year that an ancestor of Samantha Cameron, the prime minister's wife, received the equivalent of several million pounds in compensation when the British abolished the trade in humans.
Mr Cumberbatch was born in Kensington and Chelsea, educated at Harrow and has starred in a series of acclaimed films in recent years, including Atonement, War Horse, Tinker Tailor Soldier Spy and The Fifth Estate, in which he played Julian Assange, the Wikileaks founder.
In 2012 he courted controversy by lamenting that he was a victim of "posh-bashing", saying he might move to America to escape being "castigated as a moaning, rich, public-school bastard, complaining about only getting posh roles". In an interview with the Radio Times, Cumberbatch insisted he was middle class, saying that despite his public school education and classical training, "I wasn't born into land or titles, or new money, or an oil rig."
Ms Cumberbatch was born in the New York borough of Queens, graduated as a lawyer and has spent a long career in city and state government. Talking of her roots in Barbados, Mr de Blasio said that her heritage "has driven her to excellence".