During 1951, George VI's health declined and Elizabeth frequently stood in for him at public events. When she toured Canada and visited President Harry S. Truman in Washington, D.C., in October 1951, her private secretary, Martin Charteris, carried a draft accession declaration in case the King died while she was on tour. In early 1952, Elizabeth and Philip set out for a tour of Australia and New Zealand by way of Kenya. On 6 February 1952, they had just returned to their Kenyan home, Sagana Lodge, after a night spent at Treetops Hotel, when word arrived of the death of the King and consequently Elizabeth's immediate accession to the throne. Philip broke the news to the new Queen. Martin Charteris asked her to choose a regnal name; she chose to remain Elizabeth, "of course". She was proclaimed queen throughout her realms and the royal party hastily returned to the United Kingdom. She and the Duke of Edinburgh moved into Buckingham Palace.
In what year did Martin Charteris become Elizabeth's private secretary?