A few miles from the sea in Kent in the south of England, hedges of hazel, ivy and briar stand like ramparts separating kingdoms of fruit.

In one field are quinces, dense as golden anvils. Nearby are grey medlars, hard and sour. Pears gleam through red leaves. But the real stars are the apples – more than 4,000 trees, of more than 2,000 varieties. Their fruit clusters along wand-like branches and carpets the ground in a fragrant layer of softly rotting flesh. They smell of a thousand warm afternoons spent snacking in a hammock or up a tree. I kneel under the branches of a particularly laden tree to find the label with the name. It reads, aptly: "Weight."

This is the United Kingdom's National Fruit Collection, a living repository of apples once grown in the British Isles, as well as other fruit. It is not the only apple library out there. The USDA's Plant Genetic Resources Unit in Geneva, New York, and New Zealand's Plant & Food Research's collection, among others, host thousands of apple varieties.

But unlike those collections, which include wild relatives of apples, collected in Kazakhstan or on salty beaches in Alaska, to aid apple breeders in search of new traits, this collection is a record of the British love affair with the fruit. "There's a history of apple production here," says Matthew Ordidge, a senior research fellow at the University of Reading near London and the nation's curator of apples. In the lively café at the collection at Brogdale Farms in Faversham in Kent, he recalls a proclamation made a 100 years ago by apple enthusiast Edward Bunyard: "No fruit is more to our English taste than the apple."

Be that as it may, just a handful of apple varieties are grown commercially in Britain now. "Apple fruit production in the UK is not that big a business," explains Ordidge. "We only produce somewhere around 35% of home produce; we import the rest." Even the apples grown domestically are often of varieties from elsewhere, like Gala (from New Zealand), Jazz (also New Zealand) and Cameo (from the USA).

This state of affairs dates to the 1970s and 1980s, when imported apples like French-grown Golden Delicious stormed the supermarkets. When the dust settled, most English apples were no longer commercially viable.

However, once orchardists in the UK grew vast quantities of the fruit – at the end of the 19th Century there were more than 20,000 acres (81 sq km) of apple orchards in Devon alone – and what's intriguing is that the genes of those trees, whether they were Duchess of Oldenburg or Cox's Orange Pippin, live on unchanged in these fields in Kent.