My friend, a teetotaller, was intrigued by what happened next. They warmed the glasses in their hands, drank the top bit of the liqueur, set the rest alight then put their palms flat over the top. The flame created a vacuum so they could lift up the glass as if by magic to their noses. Then, on a signal, they snorted the vapours and quaffed the inferno. Reader, please. Don’t try this at home.

They urged her to have one. “Go on Lizzie, go on.” She declined, warning them about health and safety regulations in public places. “You must,” they said, “you’ll enjoy it.” The next bit reddened her face, despite her total abstinence. “It’s peer pressure,” they said. She went home flattered. Peer pressure, indeed! The wonderful inclusiveness of the young!

She hadn’t succumbed to the alcohol, and I wouldn’t have either. The nice thing about middle age is that you’ve moved on from the noisy world of Tequila slammers and Drambuie shots. Instead, I’m a wine buff. I can tell a drop of Chateauneuf du Pape from a home-made beetroot. The red wines of the Rhone lack the homegrown earthiness of beetroot. I can tell a Liebfraumilch from a nice bottle of runner bean. My home-grown runner bean wine has no chemical additives, doesn’t stink of sulphur or bring on a migraine.

I urge any non-teetotal teacher to grow and make their own wine. Besides being the only way a teacher can afford a drink (the name Teacher’s for a branded whisky is surely just a cruel tease, an ironic moniker), home-brew is a metaphor for teaching. It’s all about what we vintners call improvement and it applies equally to pupils as to wines.

Sometimes you can spoil a good vat by poking it. Sometimes you can write off a sour, moody young wine that later matures into excellence. Sometimes it just needs a shove in the right direction. Someties blending’s the answer. You get a wine that’s over robust to work with a quiet one. Or go for a whole class discussion: tip everything in the bucket together and watch them ferment.

The best home-brewers are like the best teachers. Patient. The worst are forever tipping the demijohn and drinking the stuff too early through gritted teeth, glad when they’ve had enough. They flush anything that looks a bit off down the toilet.

My late father-in-law would have made the perfect teacher. When I first told him I made my own wine, I offered him a couple of samples. “You’ll like this gallon, squire,” I told him, “but this one I’m not so sure about.” It was a stubborn runner bean that hadn’t cleared and I’ll never forget it.

“Son,” he said, “there’s no bad wines.” Such wonderful West Country optimism. Of course. Just like there are no bad kids, no learner that can’t be clarified. He kept it for a year then drank it when it was perfectly clear, and like the best of runner bean wines it tasted nothing like runner beans (e-mail me for the recipe).

Growing runner beans. There’s another metaphor for you. I plant two to a cane knowing there’s only room for one. Later, I start another lot under glass. Only the sturdiest survive.

What will it say, the one that is pinched out, apart from, “Ouch! I’m doing my best. It’s just that my neighbour has grown a bit faster and taller.” Or if both beans at the cane are pinched out and a greenhouse newcomer replaces them? “That isn’t fair,” they’ll say, “that one’s younger than we are. That hothouse upstart never had to deal with frost.” “Sorry,” I have them between finger and thumb, “but that one’s quicker than you are.” Ouch.

Maybe that’s a metaphor for becoming old and waiting for the pinch. But that’s me getting paranoid. I think back to my friend in the restaurant and her students calling her their peer when she’s the wrong side of... well, maybe the thing is to be the right side. Of any age.

Richard Hoyes teaches at Farnham college,Surrey. E-mail: richarddeaubenay@yahoo.co.uk