On Thursday, Lidl will unleash its biggest wine promotion by almost doubling its range to 48 French wines, among which there will be vintage champagne, premier-cru chablis and posh claret costing as much as £26 a bottle.

It's a long way from the discount chain's comfort zone, so I ask its buyer, Ben Hulme, whether he is nervous.

"I'm massively excited," he replies, before adding what must be the understatement of the year. "We're aware of the fact we're not well-known for being a retailer of fine wine." Nobody will argue with that, and on past trips to Lidl I've never been tempted by the drinks aisle. The wines were perhaps not bad for £3.99, but for that price you're getting a mouthful of tax and little else. There was also the sheer scale of the operation, with one man at Lidl's German HQ selecting wines for more than 9000 stores across Europe.

For this French promotion the wines have been picked by Hulme with help from Lidl's buyers in France and some masters of wine at home.

From what I have tried, those bubbling under a tenner definitely impress. With careful buying and low margins, the genuine quality of the wine shines through.

The endless half-price deals in other supermarkets, where wines jump from £10 to £5 and back again, have doubtless eroded our understanding of price and value. "I'd like to think customers are pretty savvy when it comes to that," says Hulme, "but you're right. I can tell you all day that something's the best value on the market, but it's still expensive."

Besides giving regulars a taste of the good life, he says the promotion is aimed at attracting new customers "who understand that a St Emillion Grand Cru at £11.99 is a very good price". One wonders what these Lidl virgins will make of it.

My guess is they'll be frustrated by the queues but happy not to face self-service tills. They will be wowed by the cheap fruit and veg and bemused by the non-food aisle packed with power tools, knickers, cuddly toys and the occasional cut-price sporran.