LONDON'S blue-chip shares endured a mixed ride yesterday, finishing a session marked by uncertainty on a low.

Early jitters about insurance sector dividend payments sent the benchmark FTSE 100 Index tumbling before investor nerves were settled, helping the Footsie return to positive territory.

But by the close of trading the top flight was back in the doldrums at 4137, an 11.8 point fall for the day.

London's performance also reflected a poor opening for Wall Street, where the Dow Jones Industrial Average dipped another 50 points after opening the week slightly lower.

Insurer Prudential proved a major driver for London shares throughout the session, after announcing plans to reduce its full-year dividend by 40 per cent. The shares had slipped 14p to 420p by the close after a volatile day for the stock.

Other insurers were also hit by the news, with Norwich Union owner Aviva 13p down at 484p, Royal and Sun Alliance off p at 151p, and Legal and General down 2p at 96p.

On a brighter note, healthcare group Amersham topped the Footsie risers board, with a gain of 39p to 490p, after reporting half year results in line with market expectations.

It was closely followed by United Utilities, which saw shares recover 31p to 563p after a fall on Monday when the group announced a rights issue.

Also riding high in the blue-chip index was confectionery-to-drinks company Cadbury Schweppes, which benefited from being upgraded by City analysts after promising results last week. Shares rose 13p to 379p.

Elsewhere, BP fell 3p to 419p as the market continued to digest the oil company's first half figures. Rival Shell was down 3p at 388p.

Meanwhile, cigarette group British American Tobacco saw its shares slip 4p lower to 650p, despite announcing a two per cent rise in half-yearly operating profits and a ten per cent increase in its interim dividend.

Shares in telecoms operator BT fell 1p to 205p as the company announced it was re-entering the mobile phone market with a range of products.