Here's a vivid picture of what it costs -- or seems to cost - to live a wealthy life-style in London. According to a Harris poll done for Saturday's Financial Times ("Britons say 432,000 feels like a capital fortune"), "A family of four needs a pre-tax income approaching half a million pounds a year to feel rich in London." This is eighteen times the average wage of 23,800.An adjoining article by Bob Sherwood identifies the items that make a family feel rich. It is, of course, more than a bit subjective.What would the figure be for Americans in New York or Los Angeles? Not much less, I suspect.Let's ask the Clintons.