Patry says: 'The customer pays for the wine. If they say it's corked, we swap, no problem, whether it really is or not' / Dan Burn-Forti

Patry has been in the business since a teenager in her native France, and one thing she has learnt is that the paying customer is, pretty much, always right

A friend summed up the revelatory moment at which the true worth of a good sommelier became clear to him: "I didn't know much about wine then, so I ordered a glass of Chardonnay with my foie gras," he tells me. "The sommelier looked at me for a second and, very politely, suggested sir might try a Sauternes instead. It was a glorious combination I'd never have dreamt of trying. Just wish I still ate foie gras…''

Of course there is a lot more to the job of a sommelier – more prosaically, a wine waiter – than shimmying around, polishing the odd glass, trying to upsell on the claret or suppressing a snigger after you pick the second-cheapest bottle on the list…

Actually, it is a demanding life. In a Michelin- or aspirant-Michelin-star restaurant, you start early, around 10am, and normally finish about midnight. Duties include checking that listed wines are in the cellar, those by the glass are ready, the whites are being chilled, the champagne bar is stocked and that you know all about any new wines on the list.

It is also important to be aware of the wines that best enhance every course on the menu, which almost certainly changes regularly and can be a difficult task with a chef prone to experiment with wine-challenging ingredients: chilli, say, chocolate, grapefruit and so on.

All for a daily routine of demanding punters, including those who think they know their claret from their Bordeaux, and not very much reward. A sommelier at Heston Blumenthal's two-star Dinner, for example – one of the 10 best restaurants in the world, where you cannot really eat well for less than £150 for two – earns about £21,000 per annum. At least they do wear rather fetching brown "artisan" aprons.

As group head sommelier for Jason Atherton's Michelin-starred Pollen Street Social-based mini empire, Laure Patry earns a good bit more, wears the formal dress more associated with that of a sommelier, and knows the hours go with the territory. Now 33, she has been in the business since a teenager in her native France, and one thing she has learnt is that the paying customer is, pretty much, always right.

"The customer pays for the wine," she says, giving an unmistakably Gallic shrug. "If they say it's corked, we swap, no problem, whether it really is or not. If it's very expensive, I might discuss…" That did not happen when, very recently, a diner ordered a £2,500 Petrus. If it had been corked, you'd have taken it back? "Of course."

While the diner who opts for a heavy red with a light fish dish is always, unblinkingly, respected – "I might suggest a lighter red, but if they don't want it, that's up to them" – Patry likes to encourage customers to try something new or different. But, in a modish, unfussy restaurant such as Pollen Street, do you need the traditional sommeliers' understanding of Burgundy and Bordeaux? "Absolutely. Vintages can be totally different, even from the same producer."

While great vintages and the big names can usually be bought from the more top-end wine dealers, many lower-priced wines are exclusive to restaurants and cannot be found on the high street or online. But Patry and her two counterparts at Dinner and Searcys Club at the Gherkin have now teamed up to share their wine knowledge through a new online set-up, the Wine Club – a good way, she says, of getting the sommeliers' knowledge of special wines from her favourite small producers to a wider audience.

Another tradition she challenges is that a sommelier is a man's job. Five of her nine-strong team at Pollen Street are women and she has actively promoted other female sommeliers, such as Celine Gaube at Little Social. "In England it is better. In France, it is much more traditional. But I've loved wine since my parents used to take me on vineyard trips when I was young."

Patry is pretty much at the top of her game. Working for a Francophile Yorkshire restaurateur as part of her training led to stints with Gordon Ramsay and Claridge's before Atherton snapped her up. As well as buying and maintaining the extensive cellar at Pollen Street, she supervises a total of eight sommeliers at their three other London restaurants and is helping establish Atherton operations in the Far East, exchanging emails at home after midnight. For holidays, she visits vineyards.

But enough of her loves. What is it that annoys her about customers? "Ice," comes the swift response, with a shudder. "In white wine, even in champagne. I know. It happens quite a lot. But, you know, people do what makes them happy. You just go: 'OK…'"

Seven questions your sommelier should be happy to answer

1. Could you open the Vega Sicilia while we are still in the bar, so it can breathe before we get to the Chateaubriand?

2. There is something wrong with this £50 bottle of wine; could you replace it please?

3. Can you recommend a red wine for my fish and a white wine for my meat course?

4. Do you have any English wines?

5. Can I take the rest of this Petrus home?

6. I've got a £35 limit on wine; what can you suggest that suits both my main course and my partner's?

7. We haven't ordered our main course yet, but we are thinking of drinking this excellent Gewürztraminer – can you recommend one of chef's fish dishes that would match it?