No one makes a meal of lunchtime any more This is a modern phenomenon. In the Fifties, lunch might not have been more than half an hour, but no one ate it at their desk. My friend Rachel, for instance, who worked for the Post Office, took in lunch - a curry or a pie - and would heat it up in the staff-room oven and eat it there. Her husband would go home for lunch, from his work at the police station, and so would their children, from school. Lunch was the main meal back then. It's easy to blame the shift to desk meals on the distances we travel to work. Travelling home at midday is unthinkable for many. But, as I know, working at home doesn't necessarily help with sticking to civilised eating habits. When it comes to mixing business and biscuits, I am a serial offender. Sitting down at my desk (the kitchen table) the first thing I think of is food. The horned Nigella perched on my shoulder murmurs seductively: "Just a little something would make you so much more productive." One cookie quickly becomes a packet. I had assumed chowing over the keyboard was simply a displacement activity. After all, I can't be typing away while I'm buttering toast, greasing the keys and spraying telltale crumbs in the process. But rather than a simple slide in our collective morals, it may be that our high-stress lifestyles are at least partly to blame. After one too many bars of chocolate had vanished, leaving nothing but a faint queasiness and a film of cocoa butter on my fingers, I was shamed into a bit more research. And - don't you just love science? - it turns out that it's more than simply a way of shirking work. Working for most of us is pressurised, and when we are under stress our adrenal glands produce extra cortisol, a hormone. Now, in the good old days of mammoth-hunting and cave management, a cortisol spike would have given us the energy to fend off hungry jackals or keep those pesky Neanderthals from pinching the wife. And after that fight or flight, it would give us the urge to recoup our energy with as many calories as we could. Nowadays, that's likely to translate into a craving for fat and sugar - a packet of biscuits. Mind you, we can't blame everything on stress. We have become a nation of snackers, which starts in childhood, when under-fives are encouraged to eat not to slake hunger but boredom. Parents thrust "car snacks" into their toddlers" hands as they fasten the safety seats. Whining children are given bags of sweets to shut them up. A visit to the cinema for teenagers seems to be as much about mindlessly filling their faces with bucketfuls of sugar-encrusted popcorn as watching a film. Eating in the street has even been given a veneer of respectability, with the increase in gourmet burger vans. All of which has been bad news for a proper weekday lunch. Colin Spencer, a food historian, reckons that its demise started 15 or 20 years ago when manufacturers increased the availability of snack foods. Nor does he regret it, when it comes to top-end executives anyway. A lot of time was wasted on boozy lunches that lasted half the afternoon. I think it's a good thing. All the same, it's hard not to feel nostalgic for a time when the ordinary office worker could take time away from the desk. And there may be a drift back. There are rumours that when Labour-controlled Camden council moves to its new offices in Pancras Square next year, eating at desks will be banned. Miss Soubry will be delighted, and we can all celebrate a rare bit of cross-bench agreement.