It is not certain that they have the date right. Colin Hambidge, Unwins' public relations manager, insists that he cross-checked it in two encyclo- paedias, but the garden historian Richard Bisgrove maintains that tomatoes were brought to England, from Latin America via Spain, more than 50 years earlier, in 1544. In any event, they continued to be rare throughout the 16th century, for in a 1604 account of a voyage to the West Indies they are described in wide-eyed wonder as a "great sappy and savoury grain".
Among undisputed facts is the derivation of their name from the Mexican Aztec word tomatl, although when first grown here they were called love apples because they were supposed to work as aphrodisiacs. The disappointing fieldwork that led to that name being challenged is not recorded, but at some time in the 17th century it must have fallen foul of an early Trade Descriptions Act.
For a while the tomato was known as pomo d'oro, golden apple, because the first varieties were closer to yellow than red. Today the yellow tomato is coming back into favour: to celebrate the anniversary Unwins are promoting a new bush variety called Taxi, the colour of a New York cab.
Colin Spencer, in his Vegetable Book (Conran Octopus, pounds 20), tells us that for a long time tomatoes were a minority taste: in 1597 John Gerard's Herbal noted their "rank and stinking savour". Spencer credits two gourmet Jesuit priests with popularising the red version in the 18th century.
During the present century tomatoes have become increasingly popular with gardeners because they are often expensive in the shops and some of the best-flavoured varieties are not grown commercially on a large scale. They grow quickly and are quite decorative for most of the summer. For people with no room for large vegetable plots it is a boon that, given careful watering and feeding, they adapt well to containers, where their yield can be satisfyingly high.
If you have a greenhouse you can sow seed in heat over the next few weeks and pick the first crop in June. Modern outdoor varieties, ripening a couple of months later, will thrive in most parts of the country, and in last year's golden summer many did spectacularly well. Some enthusiasts believe that those grown in the fresh air have a more tangy flavour.
Seed catalogues offer a wide selection of both indoor and outdoor tomatoes. Your choice should depend on your flavour preference and the growing conditions you can give them. The vegetable specialists Marshalls list no fewer than 22 varieties this year. Their indoor tomatoes range in size from the smallish Piranto to Big Boy, one of the huge "beefsteak" varieties that first became popular in America because the broad slices fit nicely into a hamburger roll.
In tomatoes, smallest is often sweetest, and at the other end of the size range come the increasingly popular cherry-sized fruits, usually grown outdoors. Most catalogues list Gar-dener's Delight, one of the longest- established and some say still the best-tasting of the small ones. It is not an Fl hybrid, so its yield can be lower than some of the newer versions such as Supersweet 100 and Cherry Belle.
In recent years several growers of these small tomatoes have switched allegiance to the delicious orange-coloured Sungold, introduced by Thomson and Morgan in 1992, claiming superior flavour. This year Dobies are launching Yellow Debut, which from the catalogue picture looks similar to Sungold.
For even greater novelty you could try Tigerella, another non-hybrid, whose medium-sized fruits are striped red and gold. Moving up in the size range again, a popular choice is Marmande or the newer Super Marmande, outdoor tomatoes adapted for British climates from the lumpy but wonderfully flavoured French variety that became popular some years back, after people had enjoyed it steeped in olive oil and vinegar on Mediterranean holidays.
Tomatoes have two distinct habits of growth and have to be treated accordingly. All those I have mentioned so far are cordon-grown, usually on a single stem - although there is an incipient fashion for fan-training them against a wall from several stems. Limiting growth to one stem involves constantly nipping out side shoots as the plants develop, and all cordon tomatoes need some kind of support as they grow taller.
The bush varieties - they include Sleaford Abundance and Red Alert - are less trouble. They grow into low plants that do not normally need support or the removal of side shoots. The drawback is that the bushes can get untidy and the tomatoes themselves may sag to the ground, where they are prey to snails and other pests. A few varieties, Gardener's Delight among them, can be grown either as cordons or bushes.
A popular bush tomato, listed in most catalogues, is Tumbler, bred for growing in a restricted space in a hanging basket or tub. The plant stays compact and the fruit is cherry sized. Totem is similar but a little larger.
Plum tomatoes (more usually seen in cans from Italy than growing in the garden) make larger bushes. Dobies have a new one this year called Incas, while Thomson and Morgan offer Brigade, which has oddly squarish fruit recommended for sun-drying.
I grow tomatoes in two ways. Most years I have about 10 plants in 10in pots standing on steps behind the house. The garden faces south, so they get plenty of sun and are protected by both house and garden wall. I also have between six and 10 plants on my allotment, depending on the space available at planting-out time, when the plot is at its most crowded.
I try to ring the changes and last year I grew Supersweet 100 and Dario, a large-to-medium fruited variety from Marshalls. In the beefsteak range I had an American variety called Celebrity.
I sow the seed indoors in early March and plant them out in May. For the pots I use a peat-based multi-purpose compost, because I have not found a peat-free product that holds moisture nearly as well. Watering is always a difficulty with tomatoes, and in the fiercest part of last summer, even with daily watering, they were beginning to droop before evening.
The problem is even worse if you grow them in growing bags (purpose-made plastic bags filled with compost) which get very hot very quickly. You can, however, now buy attachments for the tops of the bags which contain deep water reservoirs and should help keep the plants happy.
Once the trusses start to set I add a standard tomato food such as Phos- trogen to the water at every second watering. Yet however carefully I water and feed it is very hard to avoid blossom end rot - a blackening of the fruit on the side furthest from the stem. The first fruits to ripen are always worst affected, and as summer progresses the problem eases. Blossom end rot seldom occurs in tomatoes planted in the open ground.
One indulgence I allowed myself last year was a single white tomato - from the Henry Doubleday Research Association's list of endangered vegetables - that I bought as a seedling when visiting a garden in the Cots-wolds. It grew vigorously in a pot behind the house but produced only about 10 fruit, not exactly white but pale yellow. Their flavour was on the bland side.
The Supersweet behind the house began to ripen first, in early August, but those in the allotment were not far behind last year. They are as delicious as their name suggests but I too thought that Sungold, which I grew the year before, just had the edge in flavour. Dario - juicy and sharp - matured next while Celebrity, clearly used to the California sunshine, was a week or two behind.
The Supersweet yielded better on the allotment than in pots: perhaps they like to spread their roots around. Both the larger kinds, though, produced better crops in the pots on the steps, where they continued to ripen until early November.
Tomatoes are satisfying to grow but are not the easiest of vegetables and, even in this celebratory year, I would recommend them only to people prepared to offer the necessary commitment. They are as much of a tie as pets; if you go away at the height of summer, even just for the weekend, you have to arrange for someone to look after them. So before you blithely sow the seed in the next few weeks, remember the hot days of summer and the trudge to and from the house with the watering can, and examine your motives.
SUPPLIERS: Ring the following for seed catalogues from firms mentioned above and others with good tomato lists: Chase Organics 01932 820958; Dobies 01803 616888; Johnsons 0800 614323 (Free-phone); Marshalls 01945 583407; Suttons 01803 614614; Thomson and Morgan 01473 688821; Unwins 01945 588522.