The 31-year-old was among 14 people killed in a vehicle attack on New Year’s Day.

His stepmother Alexandra Pettifer, previously known as Tiggy Legge-Bourke, cared for Prince William and Prince Harry in the 1990s.

Prince William said: “Our thoughts and prayers remain with the Pettifer family and all those innocent people who have been tragically impacted by this horrific attack.

“This comes after palace sources said King Charles was “deeply saddened” by the death and has been in touch with Mr Pettifer’s family.

The 1 January attack saw a 42-year-old US Army veteran drive a pick-up truck into crowds along New Orleans’s famous Bourbon Street before being shot dead by police.

The New Orleans coroner gave Mr Pettifer’s preliminary cause of death as “blunt force injuries”, PA reports.

In a tribute, Mr Pettifer’s family described him as a “wonderful son, brother, grandson, nephew and friend to so many”.

Prince Harry has also been informed but will not be commenting publicly on the news.

The suspect, named as Shamsud-Din Jabbar, is believed to have acted alone in a “premeditated and evil act”, the FBI said.

It added that a flag of the Islamic State group was found inside the vehicle.

Two improvised explosive devices were also found nearby, according to police.

A well-known American college football player, a young aspiring nurse and a mother of a four-year-old are among the victims.

At least 39 people were also injured during the attack, which took place in the city’s French Quarter – a bustling nightspot popular with locals and tourists – at around 03:15 (09:15 GMT) on Wednesday.

Some of the injured have been discharged from hospital – but more than a dozen remain, with some being treated in the ICU.

Mr Pettifer, of Chelsea, London, was named by the Metropolitan Police as among the victims on Saturday morning.

His family said in a statement they were “devastated at the tragic news of Ed’s death in New Orleans”.

“We will all miss him terribly. Our thoughts are with the other families who have lost their family members due to this terrible attack.

“We request that we can grieve the loss of Ed as a family in private. Thank you.”

In a statement, the Foreign Commonwealth and Development Office said it was supporting Mr Pettifer’s family.

Ms Pettifer joined King Charles’s staff in 1993 when he was the Prince of Wales.

She became a close companion to the young princes following the separation of Charles and Diana, Princess of Wales.

Ms Pettifer often accompanied the two princes on holiday and, following the death of Diana, she helped them adjust to the loss of their mother.

In 1999, Ms Pettifer – née Legge-Bourke – married security consultant Charles Pettifer at a private ceremony in Wales, which was attended by William and Harry.