Share prices on the London Stock Exchange were little changed Thursday amid some profit-taking and uncertainty over the market's direction. The Financial Times-Stock Exchange 100-share index was off 0.4 point, or 0.02 percent, at 1,878.9. Trading volume was 558.9 million shares, compared with 521.6 million shares Wednesday. Analysts said the market appeared to be consolidating the advances of the previous two sessions, when the key index climbed 35 points. ``People are starting to question whether the rise to 1,900 is sustainable,'' one trader said. Roger Charlesworth, senior dealer at Chase Manhattan Securities in London, said the market was having a delayed reaction to Wednesday's news of a half-point rise in the British commercial banks' base lending rate to 9 percent. Higher rates, he said, ``might be quite bearish because it's not to wring inflationary pressure from the economy but rather to stabilize the currency.'' News that Rowntree PLC had decided to accept Nestle S.A.'s sweetenend takeover offer of 2.55 billion pounds, or about $4.5 billion, continued to support selected issues in an otherwise declining market, dealers said.