By EILIDH MACASKILL

Last updated at 11:45 06 August 2007

The airline industry is not, it has to be admitted, a pretty sight. What with BA's fines of £270 million for price-fixing, public disgust at the state of Heathrow Airport and the unwieldy carbon footprint, air travel looks about as healthy as Lindsay Lohan's career.

However, if you were to ask the average customer which single issue really grates, it would be the sheer volume of lost luggage, which this year is at record levels.

In 2006, 24 of the largest airlines lost 5.6 million bags with, surprise surprise, BA being the worst culprit. According to the Air Transport Users Council, the airline lost 23 bags per 1,000 customers in 2006.

And, incidentally, lose your bags on a BA flight and you have a very short time in which to make your complaint.

While Air France allows 21 days for you to calm down, go home and report your case lost, BA insists that you queue up and do it immediately. It will then pay up to £800 per bag - which doesn't even cover some people's monthly shoe habit - if it isn't located within 72 hours.

But have you ever wondered what on earth happens to all those lost bags? The truth is, that if you have travelled in the past six months and lost your luggage, there is a chance (albeit a slim one) that I have your case. I didn't steal it. I bought it, at auction, in the full knowledge that I was purchasing someone's precious cargo.

It's a roaring trade, but one that only those in the loop know about.

Christine Sachett is one such person. A no-nonsense yet affable businesswoman, she has been running her father's business, RF Greasbys Auctioneers, situated in a scruffy sidestreet in Tooting, South London, for 33 years.

Every week, she auctions off an average of 90 pieces of lost luggage - roughly 4,600 lost bags a year. But, while BA has announced its worst year ever for losing our gear, Sachett claims the number of bags going through her business has actually decreased.

"It doesn't mean fewer bags are being lost, just that the tracking and relocation systems have improved worldwide. More bags are returned," she says.

This is a fact backed up by the Department of Transport statistics, showing that only 0.005 per cent of all checked-in bags are permanently lost.

But those that do go astray will end up in an auction house like Greasbys.

Aside from lost luggage from baggage handling companies, they also sell goods on behalf of HM Revenue & Customs, Transport For London, the Metropolitan and Sussex police authorities, various county courts and bailiffs, and major airline companies.

Once a baggage handling company deems a piece of luggage to be completely untraceable - three months in lost property is the usual time frame - it is shipped off to an auctioneers such as Christine Sachett's, where the staff rifle through the cases removing obvious valuables, personal items like photographs and anything remotely nasty before putting them under the hammer.

Bags filled with clothes are put in one lot, while electronic items, shoes (Christine has a regular clientele who deal in secondhand footwear), jewellery, duty free and toiletries are all sold in separate lots at the same auction.

It seems like a fashionista's (or voyeur's) dream, and I have come to Greasbys with hopes of bidding for Kate Moss's lost luggage or perhaps a case full of Prada clothes intended for an advertising shoot. But since you buy the suitcases without seeing the contents, it is a very tricky business.

Even if you get your hands on a Louis Vuitton trunk, don't expect to find full-on designer kit inside. The Miu Miu swimsuit, Marni sunglasses and Bottega Veneta flip flops are likely to have been removed to be sold in separate lots.

Aside from this, because of the sorting system, items are often separated from their original case. So the designer bag will probably hold economy-class Zara rather than first-class Prada.

Then there are the unexpected finds. You and I generally stretch to packing our toothbrush, travelling candle and maxi dress, but Greasbys regularly removes microwave ovens, rice cookers, blenders, African spears and crutches from the bags.

As Peter Hall, 51, a dealer and regular bidder at Greasbys, puts it: "I'd love to know what this miracle airline is - you get on needing crutches and get off walking. God only knows how these guys get home."

As for the clientele, they comprise South London car boot sale vendors, professional dealers, second-hand shop owners, enterprising amateurs and people you would expect to sell you a second-hand car (actually, Greasbys sells cars, too - maybe even yours if you default on your payments).

Amazingly, while most of us never give much thought to the fate of luggage whose loss ruins millions of holidays every year, there are people who have been avidly buying up the trolleys, holdalls and suitcases week after week for years.

"I pay for my holidays from the proceeds," says Stuart Gibbon, 38, a decorator. "It is almost a hobby. I get enough from boot sales and eBay to pay for my trip next year. Last week, I came home with a £50 case, went through it, put the Calvin Klein, All Saints and Hugo Boss stuff on eBay and woke up £170 richer."

There are no hard and fast rules for what does sell well on eBay, with stories of one man who sold ten pairs of clean, but used, cotton M&S pants for £1.

John Simpson, 24, a car boot trader, has a well-practised system. He buys the bags on Tuesdays, sorts them on Wednesdays and Thursdays, takes Fridays off, and sells his haul at car boot sales at the weekends, 52 weeks a year. "It's my job," he grins.

And there are plenty of tall tales of rich pickings. One dealer found five pairs of brand-new Armani swimming trunks, while another netted £700 from one suitcase of skiing gear.

Having said that, the profit margins aren't quite as high as they once were; cases that used to sell for £5 at auction can now go for as much as £20.

And with little clue as to content in the catalogue - "Ladies clothing"', "Toshiba TV control" or "Emile Henry fondue set" being as descriptive as it gets - bidding is pot luck.

Everyone is universally keen to avoid the homeward bound cases - although you never know which is which.

"The outward bound stuff is usually immaculate - everything washed and ironed. With homeward bound you are buying someone's dirty washing. The first thing I do is hand them over to the wife,'" says John Simpson.

While the most exciting thing I found in my three cases was an agonisingly empty Prada duster bag, certainly the auction is strangely seductive. You desperately hope to unearth something valuable while, in reality, peeking into someone's personal possessions, creating a story to fit the contents.

So although I spent a lot of time sitting on my hands in case I ended up with a lot including a crutch, 15 walking umbrellas, two folding chairs and a cricket bat, the experience induces extreme concentration, excitement and a slightly naughty feeling of bagging up someone else's property.

I haven't felt this illegal since I stole Nadine Baxter's fluffy green pencil case in primary two.

Back home with my swag: lots 143, 168, 185 (costing a total of £85.10 - I sadly went slightly overboard on the Samsonite), it was time to check out my haul.

Lot 185, a large navy hold-all, had clearly been on a skiing trip. Glamorous it definitely was not - hooded fleeces, ski jackets, jogging pants and knobbly FairIsle jumpers were tightly packed along with safe cotton pleated skirts and a rather shiny pink nylon jacket, obviously from a different case. It also featured some holiday photographs that had clearly evaded the eagle eye of the auctioneers.

Sitting crumpled on my dining room table they looked exceedingly forlorn, shots of an old man being carried on a young man's shoulders, sensibly dressed girls out drinking, a little boy with big brown eyes treading water in a pool. I wondered if the owner - still minus the case - has ever mourned the fate of the photos they'd taken on holiday.

Lot 143, the grey Samsonite case, was clearly owned by a bit of a diva - a girl who loved her waistcoats. She had four in total and rather fussy pieces by brands such as G Star and Day Birger and Mikkelson (she also liked to plump up her bust, as she'd packed her bra inserts). Think studded white cowboy shirts and animal print and diamante bikinis and you get the picture.

I will never know what she had in the Prada duster bag. I can only hope she took it on as hand luggage.

Lot 168 is a mystery - leather pants, suede shirt, neat cotton jumpers and a single very flowery pair of patterned silk pyjamas. I am thinking Japanese or Canadian with a very neat personality.

Thankfully, all the underwear was conveniently packed in net zip bags. No designer gems, no expensive jewellery, and no illicit love letters I could exploit for my first novel.

I just feel a bit grubby and more than a little voyeuristic. Still, there is always next week.