Briton killed in New Orleans was stepson of former royal nanny

British police have named one of the victims of the New Year's Day attack in New Orleans as Edward Pettifer, a 31-year-old from London whose stepmother was a nanny to Prince William and Prince Harry.

He was among 14 people killed by a US Army veteran who had pledged allegiance to Islamic State and rammed a truck into a crowd of revellers.

"The entire family are devastated at the tragic news of Ed's death in New Orleans," Pettifer's family said in a statement issued by London's Metropolitan Police.

A royal source said King Charles was deeply saddened to learn of Pettifer's death and had been in touch with his family to pass on personal condolences.

Pettifer's father Charles, a former British army officer, married Tiggy Legge-Bourke in 1999 shortly after she had stepped down as nanny to William and Harry.

The family remained close to British royalty and Pettifer's stepbrother Tom was a page at William's wedding in 2011.