London and Beijing capped their status as Olympic cities by announcing an unprecedented exchange by loan of archaeological treasures over the next five years. This could lead to one or more of China's world-famous terracotta warriors going on show at the British Museum and to Chinese crowds having their first chance to see Egyptian mummies and cuneiform tablets from London. The directors of the British Museum and Victoria and Albert Museum, who are in China with Tony Blair, unveiled the exchange deals after two years of secret preparations.