We may work the longest hours in Europe and take only 28 minutes to buy and eat our takeaway lunch, but busy British office workers make up for it by making sure we reward ourselves.

No longer willing to pack our own home-made cheese and pickle sarnie, now we demand environmentally sound coffee, organic milk, tortilla wraps, freshwater crayfish and locally grown tomatoes, all packaged in right-on recyclable materials - and it seems there's no shortage of high-street outlets to pander to our pampered appetites. With premium prices to match, the modern midday meal is becoming a legend in its own lunchtime.

A sure sign that the notion of eating quickly and well is taking a grip on the national psyche, even in Scotland, is the price put yesterday on Pret a Manger, the upmarket sandwich chain. As soon as the hugely successful small company - whose bullish strapline is Eat with Your Head - was said to be considering a stock-exchange flotation, it was valued at up to £280m. With a projected growth rate of 25 new shops a year, it appears to be a sound prospect for potential investors. Not bad for an outfit started by former chartered surveyor Julian Metcalfe in 1986 to promote something as simple as fresh food for lunch.

Metcalfe did not invent the upmarket lunch sandwich; the credit for that must go to M&S. But, at the age of 23, he and a friend from university, Sinclair Beecham, borrowed £17,000 from a bank, bought the rights to the name from a shop that had just closed, and opened their first Pret a Manger deli on Victoria Street, London. In the beginning, Metcalfe cooked everything himself.

These days Pret is a long way from a small-scale local deli. One-third of the business is owned by McDonald's, and underneath the shiny shop counters and right-on branding, it's still churning out fast food - albeit of the premium packaged, preservative-free variety.

Pret has six shops in Scotland (all in Edinburgh and Glasgow) out of a total of 160 in the UK, which have become major contributors to the London-based company's £8m annual profits since the first one opened five years ago. An ad-hoc survey yesterday confirmed that its miso soup, bread-free salads and fruit compotes are favourites with Glasgow city-centre office workers.

Pret freely admits it's only too happy to encourage customers to eat indulgently, which means mayonnaise, cheese and chocolate are allowed alongside fresh salads, soups and sandwiches. "People are much more aware of the benefits of eating the premium products in moderation, rather than wolfing down vats of low-fat chemical food," says commercial director Simon Hargraves. "They know eating a rounded diet is better than constantly counting calories or fat. We are fast food, but we're not fodder."

A kitchen in every store means tomatoes are sliced every day - unlike some commercial brands, whose sandwiches are made up to eight days in advance of distribution, and gas-flushed to prolong their shelf life. The term "long-life" is anathema to the company, which donates all unsold product to charity at the end of every day (and feeds some of our politically correct aspirations at the same time).

Pret is far from alone. Eat, a London-based wholefood takeaway chain which has just opened its first Scottish outlet at Edinburgh Airport and supplies several upmarket sandwich bars, also hand-makes its soups, salads, wraps and sandwiches in-store every morning. Good eating is also the stated priority of the American sandwich chain Subway, which also makes its sandwiches on the spot and now has more outlets in the UK and Ireland than KFC, Burger King or Pizza Hut. The fastest-growing franchise in the world, it markets itself as "an alternative to greasy, fatty fast food" and has a best-selling range of sandwiches with only six grams of fat.

Subway's advertising campaigns have made much of the American student Jared Fogle, who attributes his loss of some 110 kilos (around 17 stone) to eating its sandwiches. He has now become an official spokesman for the company.

Subway's younger customer demographic suggests it is winning the battle with the more conventional fast-food chains. Calum Macintyre, a 14-year-old from Paisley, makes a point of visiting his favourite Glasgow branch every Saturday with his friends, and says: "It's much healthier than McDonald's and offers a much better choice, which we all prefer." His particular favourite is ham with "loads of salad and tomatoes" on herby bread.

It's all about helping us make good choices rather than nannying us into doing the right thing, says Dunfermline-based nutritionist Carina Norris. "People don't like being told what to eat, and you can't force them to eat something, but there's no doubt more people are demanding better choice," she says. "A variety of good foods increases the likelihood of more people getting a balanced and therefore more nutritious diet. The more good stuff on offer, the more likely it is that the bad stuff will get squeezed out."

She warns against hot white panini or ciabatta rolls loaded with melted cheese, however, and says a wholemeal sandwich with low-fat ham or chicken is better.

But is it possible to retain the ethical side of a small food company and feed our growing demands at the same time? Richard Reed, a co-founder of Innocent Drinks - a fresh fruit smoothies company, which supplies hundreds of sandwich-shop outlets in Scot- land - thinks it is.

"We absolutely believe that it's possible to grow while sticking to your core values and continuing to offer a product that consumers want," he says. "You shouldn't compromise the way you do things just because you're getting bigger."

Innocent is currently petitioning Downing Street to have the VAT on smoothies and fruit juices reduced to 5%, and has already got 10,000 signatures online. VAT is currently charged at full rate on healthy fruit juices and smoothies, whereas many other foods, including hotdogs and chips, remain tax-free.

Simon Hargraves explains that Pret already has four Scottish suppliers, including coffee company Matthew Algie, and is looking to open new shops north of the border. "We're not that big yet - we're not Starbucks or Costa - but we're a good option on the high street," he says. "But Aberdeen, for example, is harder to get to for our distributors than Glasgow and Edinburgh. In theory, Paris is easier for us to get to than Scotland.

"But although expanding while retaining a fresh daily food ethos and reducing carbon footprint is a challenge, it's by no means impossible. It's actually easier for small companies to buy British. It's a matter of finding a network of small suppliers who can meet our specification and grow with us."

It seems our ever-growing hunger for "home-made on the high street" has yet to be sated.

Small in scale, big on taste

At the smaller end of the scale, Michael Ferguson, founder of Naked Soup in the west end of Glasgow - which also supplies a host of local outlets - finds that demand for wholesome food is high among surgeons, television producers, academics and students alike. "Our customers have a thing about our home-made lentil soup and organic porridge," he says.

Salads, sandwiches and soups are all made freshly every day from produce delivered direct from the Glasgow fruit and vegetable markets, and contain no preservatives, artificial colours or flavourings. The pastrami, brie, cherry tomato and rocket sandwich is a favourite - if not exactly low-calorie or fat-free.

"People are far more interested in well-sourced, nutritious food now," says Ferguson. We're also prepared to pay higher prices for it.