Britain's richest people have experienced the biggest-ever rise in their wealth, according to the Sunday Times Rich List. Driven by the new economy of Internet and computer entrepreneurs, the wealth of those at the top of the financial tree has increased at an unprecedented rate. The 12th an- num Rich List will show that the collective worth of the country's richest 1,000 people reached nearly 146 billion by January, the cut-off point for the survey. They represented an increase of 31 billion, or 27%, in just 12 months. Since the survey was compiled, Britain's richest have added billions more to their wealth, thanks to the continuing boom in technology shares on the stock market. This has pushed up the total value of the wealth of the richest 1,000 to a probable 160 billion ac- cording to Dr Philip Beresfod, Britain's acknowledged expert on personal wealth who compiles the Sun- day Times Rich List. The millennium boom exceeds anything in Britain's economic history, including the railway boom of the 1840s and the South Sea bubble of 1720. 'It has made Market Thatches boom seem as sluggish as Edeward Health three-day week', said Beresford. 'We are seeing billions being added to the national wealth every week.' William Rubinstein, professor of modern history at the University of Wales, Aberystwyth, confirmed that the growth in wealth was unprecedented. 'Among all of today's wealth has been created since the industrial revolution, but even by those heady standards the current boom is extraordinary,' he said. 'There is no large-scale cultural opposition or guilt about making money. In many ways British business attitudes can now challenge the United States.' Although the Britain's richest are experiencing the sharpest surge in wealth, the rest of the population has also benefited from the stock market boom and rising house process. Last year wealth rose by 16% to a record 4,267 billion, according to calculations by the investment bank Salomon Smith Barney. In real terms, wealth has increased by more than a third since the late 1980s. Much of the wealth of the richest is held in shares in start up companies. Some of these paper fortunes, analysts agree, could easily be wiped out, although the wealth- generating effects of the Internet revolution seem to be here to stay. A Sunday Times Rich List confirms that people are becoming wealthier younger. It includes the 60 richest millionaires aged 30 or under. At the top, on 600m, is the 'old money' Earl of Iveagh, 30, head of the Guinness brewing family. In second place is Charles Nasser, also 30, who launched the Clara - NET Internet provider four years ago and is worth 30Om. The remaining eight in the top 10 young millionaires made their money from computing and the Internet. The 'cut-off point for the survey' in part. 1 refers to______.