LONDON, April 6 (Reuters) - King Charles has given his support to research that will examine the British monarchy's links to slavery, Buckingham Palace said on Thursday, after a newspaper report said a document showed a historical connection with a transatlantic slave trader. The Palace highlighted a speech Charles made to Commonwealth leaders last June, when he said: "I cannot describe the depths of my personal sorrow at the suffering of so many as I continue to deepen my own understanding of slavery's enduring impact. See here for a complete list of exchanges and delays