[3] Percy was returned to Parliament for Kensington South in a November 1895 by-election, replacing the ennobled Sir Algernon Borthwick.

Lord Percy died in Paris in December 1909, aged 38, from pleurisy caused by pneumonia.

He had rallied to some extent yesterday afternoon, and it was hoped that a change for the better had set in, but early this morning a fresh crisis took place, to which he succumbed.His brother Lord William Percy and sister Lady Victoria Percy, who had traveled to Paris when they learned of their brother's condition, were with him when he died.

[6] A decade later, unfounded rumours circulated that he had been murdered on the orders of Winston Churchill, who was unpopular at the time because of his role as mastermind of the disastrous Gallipoli campaign during the First World War, when he served as First Lord of the Admiralty.

Churchill's mild-mannered brother Jack was whispered to have been the unlikely perpetrator of this act,[8] because Winston was "too cowardly" to do the deed himself.