Media playback is unsupported on your device Media caption Every Bramley apple can be traced back to one 200-year-old tree

While British summer fruit harvests are having a bumper year, apple growers are watching their crops closely in case the drought in parts of the UK worsens. The British eat their way through billions of apples each year, and it's the nation's love affair with the fruit that has made it so popular today, writes horticulturalist Chris Beardshaw.

For centuries the apple has captivated us, but it's tricky to cultivate because apples are promiscuous by design. They have a more complex genetic make-up than any other fruit.

If you were to plant the pips from the Cox in your lunch box they almost certainly wouldn't turn into trees bearing fruit anything like the original. Apples require pollinators to take the pollen from one plant and transfer it across into the flower of another.

It's that crossing of pollen that creates the most wonderful genetic exchange. Every single pip is potentially a new variety that could fall anywhere in the spectrum of small and sour to big and juicy.

Some of the world's best-loved apples, like the Braeburn and the Bramley, were discovered growing as chance seedlings, gifts from nature that just happened to taste good. The Granny Smith was discovered growing out of a rubbish heap in Australia.

So while the apple seeks only to multiply rather than reproduce the same delicious fruits, man had to fathom how to clone it with an ancient process known as grafting, which remains the same to this day. With the discovery of grafting we could clone our favourite apple trees again and again.

Apple facts Britain once produced the most apple varieties in the world

70% of apples sold in UK are imported

2300 varieties preserved in National Fruit Collection

Thomas Andrew Knight created first hybrid apples

45% of apples grown in UK are used to make cider Find a variety on BBC plant finder How to look after apple trees Tips on growing apples

The Bramley, one of Britain's most prosperous and time-honoured apples, was planted 200 years ago in Nottinghamshire. That first tree was grown from a pip by a young woman, Mary Ann Brailsford, between 1809 and 1815. Since then every single Bramley apple ever eaten and tree planted has originated from it. That's a lot, with the Bramley apple industry is worth £50m today.

The pip most probably came from an apple on a tree at the bottom of her garden. The seedling produced such fine apples that in 1837 a local nurseryman asked the next occupier of the house, Matthew Bramley, for his permission to graft scions from the tree. Bramley agreed as long as the apples bore his name. Ms Brailsford never knew the fame her apples achieved.

This original Bramley tree still stands today and the proud custodian is Nancy Harrison. Aged 90, she has spent many years admiring the tree. She grew up next door and such was her enthusiasm for it she bought her neighbour's house when the opportunity arose - and with it her beloved tree.

"I paid £500 for the house," she says. "We knew it was a wonderful apple because there's nothing cooks like it, we always loved it. We've never climbed the tree or anything, nobody's been allowed to damage the Bramley at all."

The 1944 fruit census tells us by that time there were already more than two million Bramley trees in existence.

While the Bramley was a chance seedling, many apples owe their existence to a process known as cross breeding - taking two desirable fruits and creating a hybrid.

Breeding frenzy

One of Britain's greatest contributions to the history of the apple was the result of ferocious Victorian one-upmanship amongst head gardeners, who were seeking perfection in the kitchen gardens of the nation's great stately homes.

One man in particular changed the course of the apple's future - Thomas Andrew Knight, later president of the Royal Horticultural Society. He didn't want to simply grow perfect specimens, he wanted to be able to control the taste, colour, texture and size.

He believed he could engineer and improved apples by playing the part of the bee. With meticulous precision he set about impregnating the seed of one variety with the pollen from another. After decades of patient trial and error the first hybrid apples were born.

Find out more Garden designer and horticulturalist Chris Beardshaw's British to the Core was broadcast at 2100 BST on BBC Four on Wednesday 15 June Watch the programme on iPlayer

What followed was a breeding frenzy as head gardeners everywhere began to produce new and wondrous breeds to dazzle their masters. It was a cut and thrust business.

"The fear factor was the main motivator," says Mike Thurlow, head gardener at Audley End House in Cambridge. "That's why head gardeners were always looking to be able to deliver something new, a novelty to the table."

Thanks to the passion and dedication of Victorian gardeners Britain once produced more varieties of apple than anywhere else in the world. There were well over 2,000 varieties to choose from, including Hoary Morning, Blenheim Orange, Knobby Russet and Laxton's Epicure. You could have eaten a different one every day for more than six years.

These days we are most familiar with just a handful of varieties. We may produce billions of apples a year in Britain, but sadly 70% of those are imported.

The old Victorian varieties have dwindled, many lost to the hedgerows. But we can breath a sigh of relief for the 2,300 varieties of apple preserved in the orchards of the National Fruit Collection. With the rising demand for British produce the future for UK commercial apple production is looking good.

But if these exquisite heritage varieties, like the Keswick Codlins and the Pitmaston Pineapple's that I grew up with, are to keep going then the responsibility lies largely with the British public to be their custodians and guardians for the future.