Jack Burnell-Williams, 18, died on Wednesday after being found unresponsive at Hyde Park Barracks in Knightsbridge just before 4pm, the Army said.
“It is with sadness that we can confirm the death of Trooper Jack Burnell-Williams on September 28, 2022 at Hyde Park Barracks,” an Army spokesman said.
“Our thoughts are with the soldier’s family and friends at this difficult time and we ask that their privacy is respected.”
The Metropolitan Police said the death has been referred to the coroner.
The trooper walked with the Queen’s coffin as it was carried by gun carriage through Whitehall and down the Mall following the service at Westminster Abbey during her state funeral last month, according to reports.
Police are not treating his death as suspicious.
He was believed to be one of the newest recruits to the Household Cavalry.