They say drinking wine is like drinking yesterday’s weather — which might make you wonder why anyone bothers to grow grapes in Oxfordshire.

This year, however, the record hot weather last week — just in time for the grape harvest — cheered up all concerned, including all the volunteers who turned up at the county’s vineyards to pick the grapes. But what sort of harvest did they find?

Phil Rossi of Oaken Grove Vineyard in Fawley, near Wallingford, said: “It looks like it’s going to be a good year. It started very well with the warm spring and although August was very wet, the last few days have been lovely and the quality of the grapes is up.

“You can’t tell until the wine is in the bottle, but I am quite enthusiastic.”

But over at the Hendred Vineyard in East Hendred, established more than 20 years ago and acclaimed for its English sparkling wine Hendred Brut, Viviane Callaghan said: “It’s a very small harvest and we don’t even know yet whether it will ever ripen.

“There was a frost in May which caused the problem, But we’ve still got time. We can even harvest in the frost — much the same as German eiswein is harvested.”

Ever the optimist, she added: “Harvests vary between 20 tons and half a ton! But we let the good years tide us over the bad. For instance, we have plenty of sparkling wine from last year and will be selling it here at an open day on Saturday afternoon.”

And at the Bothy Vineyard at Friford Heath, near Abingdon, owner Richard Lewicki is predicting 4,000 bottles will be produced from the 2011 vinatage, about half last year’s total.

He said: “The quality is good but the quantity is down. But the good weather is really helping with ripening — it has been remarkable.”

Mr Lewicki runs Oxfordshire’s oldest vineyard — which is 33 — with his wife Sian, who also happens to be the secretary of the UK Vineyards Association.

I asked her whether, after more than a thousand years of trying, the south of England, including Oxfordshire, was now emerging as a serious commercial wine producing region — or whether it was still an industry dominated by hit-and-miss amateurs?

She said: “It is really on the threshold of a breakthrough. True, many smaller vineyards have gone out of business in the last two years — but serious investment is going into larger vineyards, which are making real money.

“I think the future is bright so long as English vineyards concentrate on quality and concentrate on sure-fire varieties of grape.

“A distinctive and specific style of English wine is emerging. But I think it is important that vineyard owners talk to each other and avoid the kind of price war that happened in Champagne recently and brought down the quality.”

Bob Neilsen, owner of Oxfordshire’s largest establishment of this type, the 14-acre Brightwell Vineyard, near Wallingford, agreed. Just before leading 20 volunteers out to the vineyard for the harvesting this week he told The Oxford Times: “We had no frost because we are low-lying and expect a good harvest.

“It’s a serious business but you have to look at the long term. We have been here 11 years. Originally I worked elsewhere to earn the money to pour in and it could be you need to wait years for a return on capital.”

Could climate change be helping the industry?

Mr Neilsen said: “There have been several climate changes in the history of wine making in Oxfordshire.

“For instance, it was warmer when the Normans came and a lot of wine was grown here. Then it was colder in the 14th century.

“But what really hit the industry was the prohibition imposed by the Puritans in the 17th century.”

Paradoxically it seems the English wine growing business is gathering speed because a taste is developing for lower alcohol wines grown in cooler climates.

Mr Nielsen said: “In Australia they are grubbing up vines in hot areas — but planting in Tasmania.

“There are a lot of amateurs, some good, some not. You can tell a stark raving amateur if he says he is going on holiday between April and November. If you are a wine grower you must go on holiday in February.”

And back at the Bothy Vineyard Mr Lewicki, a comparatively small producer, said: “It’s a mugs’s game in this country. The only people who can really make it are those with a tourist arm and who are much larger and can build in an element of profit to tide them over the leaner years.”

Mrs Lewicki added: “We make pocket money. Enough for skiing in February.”

Mr Rossi at Oaken Grove, might be described as an enlightened amateur.

He works full-time for John Lewis in London as a space-planning manager and enjoys tending his vines, having studied viticulture in Tasmania as a 16-year-old.

But now he has managed to have his wines stocked on the shelves of Waitrose across Oxfordshire, Buckinghamshire and Berkshire and, with his expertise, could well be set to grow — particularly with the introduction this year of his sparkling rose.

But why, I asked Julia Trustram-Eave at the marketing organisation English Wine Producers, are growers from Champagne buying up land in England, when everyone knows you can only call sparkling wine Champagne if it comes from Champagne? “Perhaps they are diversifying. Or planning ahead for when Champagne country becomes warmer,” she suggested.

What is indisputable is Brits have long had a taste for home-grown wine.

The monasteries grew it before their dissolution and the Romans experimented.

During the middle ages, when Bordeaux was ruled by English kings, the wine coming to England would suggest everyone was a little tipsy most of the time.