Lloyds of London, whose bustling exchange floor has dominated the world insurance scene for centuries, is about to be challenged from across the Atlantic.

New York is the final stages of organizing its own insurance exchange with the avowed aim of grabbing a bit of the business Lloyds has enjoyed for so long.

But though no one doubts New York's financial muscle, the pin-stripesuited men of Lloyds are not dismayed. The claim it will be years before the New York venture makes a mark.

Already dubbed the Lloyds of New York, the new insurance exchange owes its birth ironically to the web of laws and regulations which has entwined the U.S. insurance business for decades.

Originally designed to protect people from unscrupulous insurers, the rules are now so complex that almost every type of insurance has to be written on officially approved forms.

Not surpringly, this stifling atmosphere has drive a lot of insurance business abroad to Lloyds and other insurance centers that can do the job quickly and cheaply.

The insurance companies tried for years to get the rules changed, but it was only in the last 12 months that they managed to persuade legislators in New York State that the city was losing business-and therefore jobs.

This powerful argument was reinforced by statistics from U.S. insurance brokers showing that nearly half of Lloydhs total business came from the U.s.**, posing the question, Why should Britain profit at America's expense?

Last spring, a group of experts from the insurance world put together two bills for the state legislature. The first created a special zone in New York free from regulation as a first step towards establishing a Lloyds-style exchange. The second provided for the exchange itself. Both bills had the powerful backing of Gov. Hugh Carey, who was due for re-election later in the year, and both passed with ease.

Next, a specially appointed committee under the state's insurance super-intendent, Albert Lewis, drew up a constitution for the exchange. By the autumn, this was ready and published for comment.

As expected, the constitution was modelled closely on Lloyds'. One committee member said: "Lloyds works. Why should we try and invent something different?"

The key Lloyds-type features are a trading floor where members grouped in syndicates write risks, free from bureaucratic control. However, the drafters made two innovations. Unlike Lloyds, where members are individuals, or "names," each liable to his last pair of socks for the risks he writes, New York members can be corporations or institutions, and they are only liable for the guarantee capital they put up as a condition of membership (about $10 million each).

Drafters said the idea is to encourage investment in the exchange and increase the volume of capital available to the insurance industry. They felt Lloyds-type liability woudl frighten potential investors away.

The draft ran into some last-minute objections from members of the state legislature who felt it discriminated against foreigners and gave the insured insufficient protection against the failure of a syndicate. But after some changes, the constitution was passed on March 1 and the exchange became a reality.

It still needs to be organized and housed, something that will tak eseveral months more. But its sponsors hope it will open for business around the end of the year.

The exchange will write three main types of insurance: reinsurance (spreading the insurance load by reinsuring an existing risk with another underwriter), foreign risks and all risks which other New York insurers have turned down. And thanks to the free-trade-zone laws, the exchange also will be able to insure those unusual risks lika a film star's legs that normally go to Lloyds.

But how serious a threat does this post to Lloyds of London? Initially, not very. If all goes to plan, the exchange should open with about 20 syndicates with about $3 million each, making total capital of $60 million.

As a rule, syndicates write risks worth three times their capital, which means that New York will start by writing about $180 million worth of insurance. By comparison, the world insurance market is worth $60 billion, making New York's contribution a mere drop in the bucket.

This is why Lloys remains unflapped by the New York venture. But in the longer term, things could change. Superintendent Lewis said "Lloyds could do with a bit of competition," and he argued that once the exchange and its credibility are established, growth could be rapid.