London Stock Exchange is not for sale. That was the defiant message at the LSE's annual meeting yesterday from its chairman Gibson-Smith.

"The board is totally focused on continuing to deliver a strong performance which will increase value for shareholders," he said.

"We will not allow these objectives to be undermined by any transaction that is ill-thought-through, defensive, or because it is fashionable."

The LSE's value was built on the unique characteristics of the London market that cannot easily be replicated.

" Issuers, in vestment banks, brokers and investors are drawn to London by our regulatory approach, the high standards of corporate governance and the deep pools of international capital that reside here," Mr Gibson-Smith added.

"What happens to the exchange matters deeply to London's international financial market and the continued global success of that market. Our futures are inextricably linked."

A merger with another exchange might lead to the erosion of these attributes through the import of unsuitable regulations and in compatible market models, he warned.

Earlier, the LSE reported a bumper start to its new year yesterday with revenues of £84.3 million, in the three months to June, 25 per cent ahead of those in the same months last year.

Clara Furse, chief executive, said this performance was driven by record volumes across its electronic trading screens and growth in the number of terminals taking its data.

That, she added, reflected not just increased trading in the particularly active markets over the last few weeks, but a more fundamental secular change in equity trading over the past year.

"The continuation of very good trading underlines the value arising from our unique strategic position and our confidence in the step-change in our growth prospects," Mrs Furse commented.

Europe's biggest stock market, now 25 per cent owned by the US Nasdaq, has been a long-running bid target.

Mrs Furse said nothing about bid prospects when she presented yesterday's three-monthly trading update. The LSE's shares have tripled in value over the past 18 months as the exchange was courted by, and rebuffed, four would-be buyers.

The New York Stock Exchange, which many analysts had tipped as a fifth and potentially winning suitor, recently struck an alternative deal with pan-European exchange Euronext.