You don't have to leave London to enjoy the traditions of Britain's small market towns.

LONG before dawn, before the first alarm clocks nag, earlier than the earliest morning teas, before the first commuter trains hurtle toward the heart of the city, the day begins in London's fruit and vegetable markets. By the time so-called white-collar workers come to grips with their morning post, the rush is trailing off. And by the time the velvet-collar executives arrive, it's virtually over.

Despite modern refrigeration methods and high-speed transport, most of London's green groceries still come from the countryside fresh each day - as they have done for hundreds of years.

The site of London's main meat market at Smithfield can boast a trade record that has gone unbroken for a thousand years. City records show that William the Conqueror granted charters to the mayor and aldermen of the City of London in the 11th century to permit them to establish markets, a lucrative privilege that they guarded jealously.

In the 17th century, Charles II, in urgent need of funds, sold a few charters himself. One went to a certain John Balch for a market at Spitalfields, on the east side of the city. In the 18th century, the area became a center for the Huguenot silk weaving industry and a particularly imposing church was built by Nicholas Hawksmore. This still dominates the Victorian market buildings completed in 1896.

Business at Spitalfields starts at 2 a.m., and the pace is fast. Traders have no computerized price lists to help them. They have to assess the strength of the market moment by moment; prices for the vegetables, fruit, and flowers sold here rise and fall rapidly. This is no time to be only half awake. The general public is not encouraged to come. Although such markets were originally built for the public, the increase in population has turned them into centers for wholesale trade, supplying hotels and retail shops. Some traders refuse to sell anything to the public. But if you are ready to buy in quantity, many stall holders will sell produce by the case. (But be prepared: they may charge retail prices. You must seek out the few who are willing to sell single boxes at wholesale prices.)

Among the charters sold by Charles II - and certainly the most famous - was the one that went to Francis, Earl of Bedford for establishing a market at Covent Garden. This was originally sited to the west of the city on land once owned by a convent. The earl was engaged in creating a new residential development at the bottom of his garden, which included the first formal square to be laid out in London, designed by the architect Inigo Jones.

In 1720, Covent Garden was referred to as ``a Market for Fruits, Herbs, Roots, and Flowers, every Tuesday, Thursday, and Saturday, which is grown to a considerable Account, and well served with choice Goods, which makes it much resorted unto.'' At first rows of wooden sheds were erected in the square, but in 1830 these were cleared away and replaced with a classical market hall. Floral Hall was added in 1859 by E.M. Barry, architect of the Royal Opera House next door.

It seems curious to us now that a market should have been deliberately sited in the most fashionable square in town. Markets were always known for their tendency toward unseemly behavior. Contemporary reports indicate that the barrow-boys had a reputation for foul language; and fairs, which included an element of entertainment, were even worse. By the 19th century, the worthy Victorians were in no mind to tolerate these any longer, and many ancient fairs were abolished at that time.

But Covent Garden survived until 1974, when the traffic congestion and general inconvenience at last forced it out to Nine Elms, south of the Thames. For a while it seemed as though the heart had been ripped out of the West End; and to make matters worse, schemes were put forward to clear the historic buildings and redevelop with typical '70s office blocks. At about the same time, the great 19th-century market buildings of Les Halles in Paris were demolished in very similar circumstances. In London though, endless delays and disputes, not to mention the British Government listing of buildings of historical importance, resulted in a stalemate until the tide of redevelopment mania had turned and conservation became the thing.

Today, Covent Garden is once more alive in the West End with areas of covered stalls, while the old market buildings have been converted to small shops. Gone are the green groceries and flowers; they've been replaced with antiques, crafts, and a range of modern products. But the atmosphere of the market is probably much as it was centuries ago.

Unlike Spitalfields, Leadenhall Market welcomes the public, for this is a retail meat and fish market. It can be found close to Lloyd's new building in Gracechurch Street, in the heart of the City. There has been a market here since the 14th century, when it replaced a fine lead-roofed mansion that had burned to the ground. Diarist Samuel Pepys shopped here and bought ``a leg of beef, a good one, for sixpense.'' The present building, erected in 1881, is a delightful Victorian confection of cast iron and glass, a striking contrast to its ultramodern stainless steel neighbor. This is the place to buy one's salmon - both fresh and smoked - and the finest shell fish and game in season.