LONDON - A 4,000 year old Egyptian crown which was discovered in an English family sitting room went on show for the first time yesterday. The diadem is thought to have been taken by the present owner's grandparents from the bandaged head of Queen Mentuhotep, who died 4,000 years ago, in her tomb near the Valley of the Kings in Egypt. The owner has loaned it to an exhibition at Highclere Castle, near Newbury, in Berkshire, west of London.