Princes William and Harry joined the relief effort for flood victims in Britain on Friday, helping soldiers unload sandbags near their grandmother's residence at Windsor Castle.
Dressed in waterproofs and Wellington boots, the young royals were filmed making what appeared to be a private visit to aid soldiers in the village of Datchet, west of London.
William, 31, the second-in-line to succeed Queen Elizabeth II, left the military last year while his younger brother Harry, 29, is still in the army.
“The Duke and Prince Harry wanted to show their support to the flood victims and thought the most appropriate way of doing that was through the armed forces relief effort,” a Kensington Palace spokeswoman told AFP.
Datchet is just over 1.5 kilometres from the queen's royal residence Windsor Castle, and from the elite Eton College where William and Harry went to school.
A reporter for The Guardian - a left-leaning British newspaper not known for its royalist tendencies - spotted the two princes making the unannounced visit.
Journalist Robert Booth filmed them helping members of the Household Cavalry load sandbags onto a railway truck.
Booth said Prince William asked him “Why don't you put the notebook down and give us a hand with the sandbags?”.
The journalist said he offered but royal minders said he would not be able to.
Britain has been hit by severe flooding after the wettest January in 250 years. - AFP