By Liam Allen
Entertainment reporter, BBC News
Stuart Pilkington is the strong favourite with bookmakers to be evicted from the Big Brother house on Friday night. But how can bookies be so sure that he will be evicted?
Stuart Pilkington survived last week's eviction but looks set to go
On Friday morning, the odds for Stuart to be booted out over eviction night opponent Rachel Rice were 1/10 with some bookmakers.
That means that punters would have to place a bet of £10 to win just £1 back, plus their original stake.
In other words, according to the odds, it's extremely likely that Stuart will be evicted.
Last week, meanwhile, when Stuart was up for eviction against Dale Howard, the latter reached odds of 1/100 to be evicted with some bookies.
Which means that those placing bets would have to put on a whopping £100 bet to win just £1 plus original stake back.
MOST POPULAR SHOWS FOR BETS
1. Big Brother
2. I'm A Celebrity
3. The X Factor
4. Strictly Come Dancing
Source: William Hill
As Nick Weinberg, spokesman for bookmakers Ladbrokes says, this could be seen as being "as close to a certainty as you're going to get".
And Dale was duly evicted.
At the start of each week, as soon as Big Brother producers announce the names of the housemates who will be facing eviction, bookmakers set about deciding their initial odds.
Specialist members of staff try to decide the likelihood of viewers voting out housemates to determine opening odds.
"We take into account things like Dale's audition tape [in which he was derogatory about women] and behaviour in the house - things that the punters see as well - and that really forms our opinion," says Mr Weinberg.
In the case of Ladbrokes, the initial odds for Dale to be evicted were set at 1/6.
How the initial odds then change is completely dependent on how punters bet.
Brian Belo won Big Brother 8 despite the twins being 1/5 favourites
"I think when Dale originally went up he was about 1/6 and then it was one-way traffic - 90 to 95% of all bets were on Dale. That explains the 1/100 price," says Mr Weinberg.
As Rupert Adams of Ladbrokes' rivals William Hill explains: "If a lot of money comes in for one person they go shorter and shorter and shorter while the other goes out and out, hopefully attracting people to bet on it."
Such "short odd" bets where an event looks likely to happen - often where people have to bet at least a few pounds just to win one back - usually do win.
In this year's Big Brother, virtually every week has seen a short odd favourite being evicted.
"We now dread the weekly eviction as we are losing money every week - punters are filling their boots," says Mr Adams.
But there will always be the odd surprise, and they don't come much bigger than last year's Big Brother final.
X Factor shock
On the final day of Big Brother 8, twins Sam and Amanda Marchant - who counted as one contestant - ended up as 1/5 favourites to win.
The surprise victory of Brian Belo - at 10/3 - was a huge shock.
"When upsets happen we tend to do very well," says Mr Adams.
"What happens to a large extent is quite a lot of people make money week in, week out on the short-priced favourites and then you put the whole lot on what looked like a certainty for the twins.
"Obviously, we then do extremely well on that one.
"A good bookmaker should break even when the favourite wins and then, when the upset happens, should make a lot of money."
There was a similar shock in the last series of X Factor when Leon Jackson won the final at odds of 5/1, beating 1/6 favourite Rhydian Roberts.
Betting on reality TV shows, including I'm a Celebrity... Get Me Out of Here! and Strictly Come Dancing, is on the rise in the UK with Big Brother the key market for bookies.
SHOW FINALS - CLOSING ODDS
Britain's Got Talent: George Sampson - 7/4 favourite
X Factor: Leon Jackson - 5/1 (fellow contestant Rhydian Roberts was 1/6 favourite)
I'm A Celebrity: Christopher Biggins - 1/4 favourite
Source: William Hill
It is estimated that punters will gamble about £10m on Big Brother 9 over the course of the series with some bookies taking more than £100,000 on some eviction nights.
While it is not on the same scale as football betting and horse racing, bookmakers says year-on-year rises in reality betting mean it is becoming a "worthwhile and significant" part of their business.
One punter who has bet big stakes on short odds "for a long time" is professional gambler and Big Brother "super fan" Ed Murray.
He says he sometimes puts on thousands in order to win £1,000 back.
Mr Murray, 30, who says he has been a professional gambler for five years, explained: "If you can get 1/10 - a 10% increase on your money when the guy is virtually definitely going, then that's a good price.
"It's virtually risk free. Some of these are virtually risk free.
Leon Jackson upset the odds in The X Factor final
"But some of them aren't and [in the first week's eviction] Mario was 1/10 and he stayed against Steph."
And despite claiming to have made thousands on Big Brother, Mr Murray - who is backing Rachel to win - warns against making big bets on the show, saying it is "full of pitfalls".
Mr Murray says he has lost thousands as a result of some bets.
He advises would-be Big Brother punters to restrict bets to no more than £10.
He also advises them to shop around different bookmakers for the most favourable odds and to seek the advice of women who, he says, make up the majority of Big Brother telephone voters.
But, above all, he adds: "Don't look at it as a way to make money."