By Josie Milani
BBC Money Programme
Bingo has been a winning number for operators
The bingo industry generates billions of pounds in stake money, and employs 20,000 people throughout the UK. However, as the smoking ban in enclosed spaces is introduced, experts are predicting disaster, with up to one in three clubs facing possible closure.
The smoking ban is now in force across Wales, Northern Ireland, and will be introduced in England on 1 July.
In Scotland, 10 clubs have already closed down since the ban was enforced last April - and more are set to follow.
Bingo is played by three million people every week - more than go to Premier League football matches.
It is estimated that half of bingo customers are smokers, and many are in the habit of puffing and playing bingo at the same time, something that - post ban - will no longer be possible.
"The effect of the smoking ban in Scotland's been a lot worse than we thought it was going to be," says Neil Goulden, chief executive of Gala Bingo.
"We've actually now lost 8% of our customer base who have stopped coming altogether."
Race for the Doors
Since the ban in Scotland, many clubs have experienced a drop in admissions.
Mecca says that it may need to close bingo halls
However, the major problem for bingo clubs begins at the interval.
Clubs have traditionally made most of their money during breaks in the main bingo session.
This is when people play table top or so called cash bingo - a faster version of the main game.
Although the stakes are low, table top bingo generates significant profits - in some cases, as much as 45% of all the money taken by the club.
But gambling rules dictate that this faster and potentially more expensive version of the game can only be played during the interval, which is when smokers are heading outside for a cigarette.
Mike Lowe, manager of Premier Bingo in Kirkcaldy estimates that during the interval, more than 40% of his customers leave the hall to have a cigarette outside.
This means a significant drop in profits.
"When you look at a loss of around 40% of your bottom line, that's devastating, and I'm not sure as operators where we move from here," Mr Lowe says.
Mr Lowe has already taken drastic measures by closing down two of his seven clubs, and he fears for the future.
Scottish Health Minister Andy Kerr MSP says the ban is all about saving lives.
"The comprehensive nature of our ban was essential. If we'd had an exemption for bingo halls the same argument would have applied for the rest of the leisure industry."
But it is the small clubs with slender profit margins and without huge resources such as Premier Bingo that are at most risk of closure.
The small clubs believe they fulfil an important social role for their customers.
Former bingo caller Jim Bowen understands how much the game means to millions of fans.
"A lot of people who play bingo are widows, people whose husbands have died or are ill, and they're carers, and they manage to get two hours away from the strain and stress and demands of domestic life."
There are thousands of people who rely on their local bingo clubs to add a bit of spice to their lives.
Margaret Lithgow is a regular at the Premier in Kirkcaldy. She says if her local bingo club closes down she will have nowhere else to go.
"I'd stay in the house 24 hours a day on my own, except if my family visits," she says. "They push me to go to the bingo. They like me to go out and get mixed up with other people."
UK Bingo is dominated by two corporate giants, Mecca and Gala.
Even though they have the financial resources to adapt to the changing bingo world, they still have to battle hard to make their non-smoking halls attractive to their smoking customers.
Gala operates 171 bingo clubs across Britain with a turnover topping £400m.
It has recently recruited celebrity bingo fan Sharon Osbourne.
She has become the face of its new online bingo site.
"It's for real people and it's fun so many people enjoy it," she says.
"You can come with your mates, have a good time, have something to eat and hopefully win some money. It's very English. I love it!"
Big rival Mecca is also adapting to a smoke free future.
It has opened the first fully electronic bingo club on the outskirts of Edinburgh where it's a goodbye to the old fashioned "eyes down" culture.
Mecca hopes it will attract a new generation of younger customers.
All players have to do is tap an electronic screen when the number's are called out.
And if that is too much bother the screen automatically updates itself with the correct numbers.
Now, with less than six weeks to go before the smoking ban comes to England, the big companies are bracing themselves for closures.
Gala's chief Mr Goulden predicts trouble ahead for the industry.
"We could have 200 bingo clubs closing. This could mean an enormous number of job losses and loss of amenity to local communities."
The Money Programme: Bingo - Your Number's Up, Friday 18 May at 1900 on BBC Two.