THE ANNUAL income of registered charities in England and Wales is estimated by the Charities Commission to be Pounds 18 billion. The commission's report for 1996 says that more than 40 per cent of the charity sector's income is accounted for by just 200 charities. A total of 280 investigations were opened in 1996, up 25 from the year before. Of the 347 cases closed in the year, 74 per cent had a cause for concern substantiated. The "concerns" include fraud and malpractice.