PRUDENTIAL RECORDS BEST RESULTS IN SIX YEARS <Prudential Corporation Plc>, which earlier announced a 62 pct rise in 1986 pre-tax profits, said it had recorded its best general insurance result for six years but had not reached satisfactory levels of profit in other areas. Group Chief Executive Brian Corby told a news conference that despite returning to trading profits, the International division and the Mercantile and General division had not reached satisfactory levels. But he said he welcomed Mercantile and General trading profits in 1986 and was optimistic about both that and the International division. The acquisition of the U.S. Life company <Jackson National> had a small effect in 1986 but its full effect would be felt in the 1987 results, Corby said. The Group also intended to expand the number of its estate agency firms bought last year, and hoped they will comprise between 10 and 15 pct of total company profits in the future. "We hope they will be very profitable very shortly. We are looking for profits from the estate agencies themselves as well as the insurance products associated with them," Corby said. Prudential's pre-tax profits rose from 1985's 110.1 mln stg to 178.1 mln stg in 1986.