LONDON (Reuters) - To aficionados, it is comfort food at its best. To others, it is as appetizing as its nickname -- a "rat's coffin".

The savoury pie, a mainstay of the British diet for thousands of years, is getting a makeover as Britain sheds a once-sagging culinary reputation and top chefs return to traditional fare.

Originating around 8000 BC with seabirds baked in feathers and hedgehogs rolled in leaves or grass, the pastry-baked pie evolved from Roman times into a standby for soccer fans.

In the 19th century, the fictional character of Sweeney Todd -- the murderous barber of Fleet Street -- played on Britons' suspicions about pie fillings with an accomplice who baked his butchered victims into meat pies.

In the wake of industrialization, pies became cellophane-wrapped rubbery microwave fodder, mass-produced on assembly lines and often oozing with fat and additives.

Britain's culinary revolution has forced the dish out of hiding. New chains selling traditional hot pastry-wrapped delights have sprung up throughout the country, many with the focus on quality and fresh ingredients.

"Everyone loves a pie -- it reminds you of mum," said Martin Dewey, founder of the Square Pie chain, which he set up in London in 2001 to offer a more wholesome variety of pies. "But pies needed an update -- they had been neglected for too long."

The Daily Telegraph newspaper has described his shops as "the crusted equivalent of haute couture", and some new pie start-ups have investors salivating at the potential easy cash flow and Starbucks-like growth of small stalls offering busy Britons a wholesome, more British alternative to burgers.

"It's a great on-the-go food, easy for commuters and the time-poor, cash-rich consumer," said Mike O'Brien, a partner at Gresham Private Equity. His firm bought one of the larger chains, West Cornwall Pasty Co., for about 40 million pounds in October.

"People want healthy food, but also convenience and a proper balance," he added.

Based in the south west and building on the Cornish pasty -- a staple from the heyday of tin-mining -- the company was founded almost 10 years ago and today sells about 6 million folded pies a year from more than 50 shops located near shopping districts and railway stations.

BULKING UP

Other small companies also report fast-growing sales.

"We've been doubling our annual sales for several years running, and we're selling about 25,000 pies a year now," said Jonathan Simon, co-founder of Bristol-based Pieminister, which offers its pies wholesale, retail and online.

"It's one of those products everyone knows but is often disappointed with -- there's lots of room for high quality pies," he said.

West Cornwall Pasty plans to open 50 new shops in Britain and its new management has not ruled out its previous owners' dream of selling as far away as New York or Hong Kong.

"The Cornish pasty has all the right qualities to be a huge success around the globe," chief executive Richard Nieto told Reuters.

Part of the new brands' appeal lies in local ingredients and fillings that reflect modern Britain, with recipes stuffed with curries, coconut milk and spicy jerk chicken.

Others use online marketing: Pieminister's Web site mixes animated graphics with a link to its MySpace page, and a parody of the corporate promise: "You must promise to love your pie, enjoy him, cherish him and above all cook him properly."

They also tap into tradition, especially at West Cornwall Pasty.

"It was basically food made for miners -- the pastry was folded over to make a hard crust so the whole package would survive a trip down into the tin mines," Nieto said.

"Our best-sellers are traditional recipes like steak and Stilton cheese, but we also do vegetarian, chicken balti, and even a turkey and cranberry sauce recipe for Christmas."

At a regional level, recognition that a part of British heritage lies within a baked crust is growing as some districts seek 'protected' status for their pies.

In Melton Mowbray in central England, pork pie producers have applied to the European Union for the Melton Mowbray pork pie denomination to be given the same regional exclusivity as champagne.

"There is no reason why Melton Mowbray pork pies shouldn't have the same protection as champagne or Parma ham," said Stephen Hallam, managing director of Ye Olde Pork Pie Shoppe in Melton.

"We sent our application in three years ago, and should have a final reply within a year. The Cornish pasty is also in line at Brussels."

WHO ATE ALL THE PIES?

Celebrity chef Rose Prince, who has written books on new British cuisine and is a critic of poor, rushed eating habits that have led to rising obesity in Britain, said a search for more acceptable fast food could be driving the trend.

"I think that pie businesses have blossomed in the wake of the backlash against McDonalds and KFC," she said.

"They are seen as a more wholesome food, more homemade or hand made -- even though many are not."

Soccer fans have long known the pie habit takes a toll on waistlines: "Who ate all the pies?" is a favourite stadium chant. Prince said that, despite the emphasis on better ingredients, calorie-packed pastries do not promote a healthy modern life.

"They do not make an ideal daily meal for a commuter who rides the bus or train rather than walks or cycles to work," she said. "Pasties were Cornish miners' food, eaten by people who probably burned well over 5,000 calories a day."