In September 1940, when bombs struck Buckingham Palace, a policeman observed to the Queen: 'A magnificent piece of bombing, Ma'am, if you'll pardon my saying so.' The sense that the Royal Family was sharing in the dangers of other Londoners did much to cement bonds of loyalty. People were fascinated by such facts as the baths in Buckingham Palace having a 5in (13cm) watermark on them, to help save water and fuel. Royal Soldier Princess Elizabeth joined the Auxiliary Territorial Service in 1945. There she learned to drive and maintain Army motor vehicles. During the war's early months Princess Elizabeth and her sister Princess Margaret Rose were sent to Balmoral in Scotland. But later, despite the danger from bombs, to keep the family together they returned to Royal Lodge, Windsor, sometimes staying at Windsor Castle, too. It was from the castle that the 14-year-old Princess Elizabeth made her radio debut on October 13, 1940, in a broadcast to evacuee children. In April 1942, at the age of 16, Princess Elizabeth registered for war service and in March 1945, despite opposition from her family and the War Cabinet, she trained as a driver in the Auxiliary Territorial Service (ATS), where she was to hold the rank of a second lieutenant.