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The royal brothers made a surprise appearance with Harry's colleagues from the Household Cavalry when they visited the severely flooded town of Datchet in Berkshire.
Knee-deep in water, but maintaining high spirits, William and Harry were photographed tossing sandbags to one another as they helped limit the river's effects.
Graham Leaver, who is parish clerk of the village which lies just two miles from Windsor Castle, said that the Princes' visit had "gone down very well."
"They were very involved and wanting to know what was going on," he said. "They were very natural. To be honest, they could have walked in among people here and nobody would have recognised them looking at the way they were dressed.
According to the Daily Mail Prince Charles' sons had been wanting to lend a hand for several days, but feared that their presence would cause an unhelpful distraction from the severe situation.
Two weeks ago Prince Charles showed his support for those who had been affected by flooding in Somerset.
The Prince of Wales paid a visit to the flood-stricken Somerset Levels in South West England, and called the delay in help a "tragedy".
"The tragedy is that nothing happened for so long," said 65-year-old Charles at the reception. Locals are said to have become frustrated at how slow the recovery process is taking.