After four decades, a letter King Charles wrote to a member of the royal household has been sold at auction, and in the never-before-seen note, he mourned the death of his old dog, Harvey. Although the yellow Labrador retriever was a fond companion of the then- Prince Charles , Princess Diana reportedly talked him into giving the dog away to a member of their staff. The letter sold for £656 by London-based Chiswick Auctions, according to the Telegraph , and was sent to Lt Col Phillip Creasy, comptroller to Prince Charles and Princess Diana at the time. Creasy, who adopted Harvey from Charles, had to put the dog to sleep in 1987 and wrote to him to share the news. “You were absolutely right to take the decision you did, although it is always a desperate one to have to take,” The King responded in his letter. Prince Charles relaxes with Harvey at the 1978 Quorn Hunt Cross Country Event. (Image credit: Getty Images) Charles and Diana are pictured with Harvey at Balmoral Castle in May 1981.…