Festivals, traditionally, are where usually sane people lose their inhibitions, where money becomes a mere trifle, just tokens used in the relentless pursuit of good times.

While music festivals can turn hardcore Calvinists into substance-addled swamp monkeys, the week to come can convert the most frugal into wad-waving hooray Henrys.

So before you embark on the not-so-good ship penury, it might be prudent to read the words of somebody who gets up to this sort of thing all year round. Ralph Kemmis for example, a successful trader on the betting exchanges. So, Ralph, how's the easy life? "It's a lot of hard work. Looking at a race, watching the ground conditions, playing back races, watching the times, where the horse is travelling - it's painstaking, laborious work."

Bah.

Kemmis uses a dvd recorder, monitoring races, stopping and starting the action to compile as much information as possible on every horse. "There's too much emphasis put on trainers and jockeys, " reckons Kemmis. "In my opinion the most important aspect is the horse's ability. If you don't have that, it doesn't matter who's riding it or training it."

Back in the day, Kemmis collected about 10 years' worth of the Racing Post, studying hard every morning just trying to find an edge before running round to the various bookies. It does sound like a hard way to try and make an easy living. "I always liked maths and figures, and I used to love just watching numbers, " he explains. "But I've always had this deep sense of injustice at somebody getting something by false pretences, that feeling of somebody pulling the wool over people's eyes. I don't hate bookies, I just think they had it too easy. It was onesided, nobody else could have an opinion." This all changed with the advent of the exchanges. Suddenly everyone had an opinion.

When Kemmis was flicking through Aertel back in the day, he was often looking for something close to a '100% book'. Bookmakers want to, obviously, guarantee a profit regardless of what happens in an event. Hence, they offer prices that exceed the probability of an event. These prices are known as 'overround' (stick with us, your friends will be impressed, honest).

For example, the odds you should be able to get on the toss of a coin are even money (50/50 chance). This is a 100% book. But if you're a bookmaker, this gives you no profit, so you might offer 10-11 on heads and 10-11 on tails. These prices are overround, resulting in a book close to 105%.

The higher the book, the less value for the punter. So the exchanges offered the opportunity for punters to create their own odds, eliminating the profit margin. Suddenly, Kemmis had no need for yellow slips and little pencils.

What exchanges also offered was the option of getting out while the going was good instead of being locked in and watching from between fingers as your sure thing gets swallowed up in the mud. "More often than not, " insists Kemmis, "if I'm not happy about a selection I'll get out of it before the off.

With a bookmaker what can you do? You're a sitting duck."

Some of the more lurid tales from the exchanges come from in-running bets, as regular readers of this paper's betting column will know.

Odds can fluctuate wildly in any event, particularly a horse race. The most famous recent example was Beef or Salmon being available at 100-1 on Betfair a matter of seconds before beating The Listener in the final strides to win the Hennessy Gold Cup at Leopardstown. But such value is hard to come by, reckons Kemmis. "I'd say there's little value in [in-running bets], unless you're pinpointing a particular horse. If you're betting blind in a race I would advise punters not to do it. If you see them running and think 'this horse is running well', by the time you've clicked in your amount that value is gone."

One of the principal points in any gambling guide, of course, is discipline. So has Kemmis any advice for those limbering up for their annual gambling fantasy? For starters, don't use the 'L' word. "I don't believe in luck.

You can do everything pretty much correct and everything can go wrong and you can have bad runs. If you can go back after the event and you know everything you did was right, be happy with that.

Luck is simply a sample of events that can change your opinion."

And finally, what do you have to lose? "I wouldn't bet more than 5% of my total bank, " reckons Kemmis.

"That means you can pretty much cover long losing runs.

Lots of people would say 10%, but 5% keeps it tidy."

A euro on Kauto Star it is then.