Things are looking decidedly rocky at the British Museum - Egypt's leading archaeologist has demanded the return of the Rosetta Stone. But the museum argues that the removal of the four-foot slab that unlocked the mysteries of the pharaohs would be disastrous Just before Zahi Hawass was due to begin his lecture at a British Museum colloquium on Ancient Egypt last week, the lights blew. The symbolism was not lost on many in the audience. For the new director of the Supreme Council of Antiquities in Egypt is a man much given to rupturing what has come to be regarded as the normal order of things. While he was in London for the conference, he dropped a diplomatic bombshell. At a private dinner with the British Museum's director, Dr Neil MacGregor, he calmly announced that Egypt would be applying for the return of the Rosetta Stone.No wonder the lights fused. The 2,000-year-old relic is perhaps the Bloomsbury museum's most important exhibit. It draws millions of people each year, and is seen by more of the museum's 5.5 million annual visitors than any other single object. Until recently, Dr Hawass was the director of the Pyramids at Giza, but last year he took over as secretary general of the Supreme Council of Antiquities. He has been throwing his considerable weight about ever since.