We look at some of Britain's secret shopping malls(Getty Images)

Forget the big retail parks or the high street, some of the best shopping in these frugal times can be found in less conventional venues.

From Glastonbury to the Royal Ascot, to any of the hundreds of other outdoor events taking place across the country, you'll find secret malls that somehow manage to offer a breath of fresh air and fun instead of the same old shopping routines.

Together, they are worth hundreds of millions of pounds every year and if shoppers are willing to pay an entry fee to go shopping, there really must be something to it.

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Getting in the mood
By generating relaxation, surprise and even some hedonism, they can get us to spend freely without frowning over the cost. It's the same kind of feeling we often have about shopping when on holiday.

Sarah Harris, owner of small independent fashion retailer Forbes, took a stand at the Lincolnshire Show for the first time this year.

"It was a nice marketing event for us, to create some hospitality for our regular customers," said Harris. "We didn't set out just to make money, though we actually did."

Maureen Hinton, lead retail analyst at Verdict Research said it is the ability to know the market that gives these events their advantage. "The foot traffic at these events is very specific and for retailers it is an effective way to get the right kind of shoppers in one place," she told MSN Money.

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Vast product offering
You can find a surprisingly large array of goods and services at shows and events like these, many of them nothing to do with the event in progress.

You can buy a designer handbag, furniture, or hand-made jewellery, you can open a new bank account, apply for a mortgage or insurance, switch gas or electricity suppliers, get double-glazing, satellite TV or a new car. You can even commission an architect to design a home.

There has been surprisingly little research on the shopping impact of these kinds of events. "It's a new area," said Hinton. "There hasn't been much research on it. Retailers are looking at all opportunities and this certainly is one."

A practical example
While it might be an overlooked shopping arena, it is still a mighty one: Glastonbury music festival this year attracted almost 180,000 people.

The result is a once-a-year music and entertainment city that also eats, sleeps -- and shops.

In a 2007 study for Mendip District Council, whose boundary encompasses Glastonbury, consultants Baker Associates calculated that the festival generates £73 million in spending in the region, with an average of £293 spent per visitor per trip.

Much of the spending was generated offsite. The festival goer's daily spend typically exceeded that of a conventional tourist.

National Trust
Not all secret malls are temporary: the National Trust (NT) attracts 50 million visitors a year to its hundreds of heritage properties, parks and open spaces.

While entry is free for the charity's 3.6 million members, the 220 shops it has within those properties turn over a cool £35.7 million each year. "This generates £5.4 million in profits to plough back into our conservation work," said National Trust spokeswoman Jane Travis.

While much of the focus is on cards, stationery, plants and branded foods like NT biscuits or jam, there is a roaring trade in other items. Britain's older generations have helped more than double the NT shops' profits since 2001.

Product launches
"The high streets are full of chains," said Sarah Harris of Forbes. "But shoppers actually want a diversity of independent-minded buyers, which is what they get at shows. For us, it's all about service and knowing your customer."

The retailers who do go there must be convinced, because the costs of stands and space at big events can run into thousands.

There is also staff time, some inevitable chaos in setting up and taking down stands and the biggest worry of all: bad weather.

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Big business for some
The Chelsea Flower Show, organised by the Royal Horticultural Society (RHS), is no slouch when it comes to selling.

You can buy anything from an £18 pair of Gold Leaf gardening gloves right up to a £3,000 John Deere lawn tractor.

The RHS reckons that it generates hundreds of millions of business, both retail and business-to-business, and adds around £500 million to the London regional economy.

For eagle-eyed shoppers, Britain's secret malls are a real pleasure. "Some things of course are really expensive, but if you know where to look you can get bargains," one shopper told MSN Money.

"It's just a bit different: you don't know for sure what is going to be there. By comparison, the high street is just a bit predictable."

Related links:
Fashion's impact on the economy
The dangers of online shopping
What's in your shopping basket in 2010?