Lee-Ann Smyth started playing poker on the internet because she did not like what was on television. As a student, it was fun to spend an hour or two each evening playing poker for not much more than the price of a video rental.

Even after starting work for Halifax bank, Smyth continued to indulge her hobby. As she became more competent, so the stakes got higher and, these days, Smyth’s hobby is her job. She spends up to 10 hours a day playing poker online, earning up to £4,500 a week. She has turned a room in her house in Carrickfergus, on the outskirts of Belfast, into a poker den.

While Smyth is an exception, it is people like her who are behind much of the remarkable growth in online poker.

Last year, she was one of about 250 dedicated players who, along with their partners, joined Ladbrokes on a poker cruise of the Mediterranean. Smyth did not win on the high seas, but it was not through lack of effort. John O’Reilly, managing director of Ladbrokes’ online operations, said the ship docked every day at a European port but nobody got off, such was the appeal of the cards.

Online poker is a massive business — it is estimated that the worldwide commission earned by operators of poker sites runs at about $4.5m a day.

Last week, the growth of the market was brought into sharp focus by results from Hilton Group, parent company of Ladbrokes, and Sportingbet.com, which last year acquired Paradise Poker, one of the world’s leading poker sites.

Shares in Gaming Corporation, a little-known internet firm that owns the domain name Casino.co.uk, jumped 21.6% after it announced plans for a poker-based internet portal called Findpoker.com.

On Thursday, Ladbrokes declared that profits from its e-gaming division were up 50% to £21.3m, with growth from poker proving especially strong. Remarkably, for a business that started less than three years ago, O’Reilly said this year poker is expected to take more money than Ladbrokes’ online sports-betting service.

Two days earlier, Sportingbet delivered record profits, driven by Paradise Poker which made better-than-expected operating profits of £8m on turnover of £13m, prompting the shares to rise and push Sportingbet’s market value above £1 billion.

Nigel Payne, chief executive of Sportingbet, is delighted and said poker would continue to grow. “We think a compound growth rate of 3% a month over the next year is a reasonable expectation.”

THE BOOM in online poker is creating a whole new crop of internet millionaires but, unlike the stars of the dotcom boom, the brains behind many leading sites are wary of the limelight. When Sportingbet acquired Paradise Poker last October, the three selling shareholders made it a condition of the deal that their identities would remain secret. All that is known about the trio is that they are Canadian and are thought to have met at university before setting up their lucrative online gaming firm. Reports vary as to whether they are computer engineers or financiers and stockbrokers. Either way, they need never work again — the three shared a £170m payout.

One reason for the lack of publicity could be the legal grey area that online gaming occupies in America, but this could soon change. North Dakota recently became the first state to apply to become a legal poker jurisdiction.

“The problem with that is that it could bring them into conflict with American federal law,” said Hilary Stewart-Jones, a partner at the law firm Berwin Leighton Paisner.