Adam Thompson had just won five pounds on a British tennis player named Laura Robson and was eager to reinvest his winnings. He scrolled through the upcoming Olympic matches on his iPhone, noticed that another Brit was about to begin play and went back to the betting counter.

“There’s no football on, is there? So what else am I going to do?” the 27-year old retail worker said Monday, spending his lunch break at a King’s Cross betting parlor.

Thompson had no plans to attend any events but figured this was his way to take part in the Summer Games being played out in his backyard, a city as aristocratic as it is gritty, where betting parlors outnumber the convenience stores in some neighborhoods.

While gambling on the Olympics is prohibited in the United States, it’s big business for the host nation of the Summer Games. The industry expects to handle anywhere from $75 million to $150 million worth of bets during the Olympics, which would more than double the action from the Beijing Games.

“There’s a phrase we use in England: It matters more when there’s money on it,” said Mark Griffiths, a professor of gambling studies at Nottingham Trent University. “When there’s a side bet on the event, it makes that activity more exciting. That’s how many people will choose to enjoy these Olympics.”

While several betting parlors around London reported low interest in Olympic betting during the opening weekend, Britain’s top gambling outfits still expect these Games to provide a big boon.

“Team GB hasn’t really gotten off to a flyer here,” Rupert Adams, a spokesman for the mega-bookmaker William Hill, said of the gold-less British team, “which I think is holding people back a little bit.”

Studies predict 1 in 8 Brits will place a bet during the Olympics — about 6 million people in all — which is why all of the British gambling outfits are taking bets on virtually every competition in every sport at these Summer Games.

“It’s never going to be as big as a World Cup final or the European Championship because football is a global sport and people don’t know Greco-Roman wrestling or taekwondo quite as well,” said Jessica Bridge, a spokesperson for Ladbrokes, which operates more than 2,400 betting parlors across the United Kingdom. “But to be honest, the first weekend surpassed our expectations. We’re seeing a lot of patriotic money out there.”

Bookmakers are making sure bettors have plenty of options from which to choose. In addition to simply selecting winners, oddsmakers have created a long list of quirky propositions: Would a nude streaker disrupt the opening ceremony? Will it rain during the men’s 100-meter race? Will the Olympic Village run out of condoms? Would a flying saucer appear over the Olympic Stadium (1,000 to 1 odds)? What outfit would Queen Elizabeth II chose for the opening ceremony?

“We took a killing on that one,” Chris Middlemiss said, “because word got out beforehand what she’d wear.”

Middlemiss is the director of sports betting for Coral, which operates more than 1,700 betting parlors. Earlier this year, he created a spreadsheet of the 36 Olympic sports and told his team of a dozen oddsmakers to become experts as quickly as possible. There’s now more than 10,000 Olympic-related bets that are offered. Think LeBron James and the U.S. men’s basketball team is a can’t-miss winner? A bettor would have to lay down $8 to win $1. Odds on individual games can be even more extreme. Angola’s basketball team was a 200-to-1 underdog to upset the American women Monday.

“We want there to be something for everyone,” said Simon Clare, a spokesman for Coral.

While sports gambling is still considered somewhat taboo in many parts of the world — online sports betting is illegal in the United States, for example — it is an increasingly accepted part of British culture, an industry that’s worth $9 billion a year.

“Historically, what we’ve seen is gambling has been a bit like alcohol was,” said Griffiths, the Nottingham Trent professor. “It’s gone from being a sin to being a vice to being a socially acceptable leisure activity.”

Jacques Rogge, the International Olympic Committee president, has expressed concern about gambling interests potentially impacting competition, and the organization has a gambling committee assigned to closely monitor betting patterns in London. Still, the Olympics and sports gambling are closely aligned here. In the Stratford district, Coral’s corporate offices are located just one floor below the British Olympic Committee. One of its newest parlors is situated across from a Starbucks in a mall on the edge of Olympic Park.

With soft blue mood lighting and a wall of televisions, the parlor feels more like an Apple store than a shady backroom poker game. There’s no alcohol or smoking allowed in any of the parlors, and most are free of frills or charm.

The vast majority of bettors are Brits, most opting for horse racing or soccer action, but the parlor near Olympic Park is drawing plenty of curious tourists, said Gary Rose, an assistant manager there.

“The Americans are coming in and to their credit, they’re backing their boys and girls,” he said, “regardless of how good they are.”

Rose said one such patriot visited the parlor Monday and despite 200-to-1 odds, bet five pounds (less than $8) on an American swimmer.

“I thought it was quite crazy, to be sure,” Rose said. “But she said she wanted to take the slip home and frame it.”

While the Olympics were a massive undertaking for the British gaming companies, oddsmakers must continually monitor each day’s events to tweak the odds and create new propositions. A huge share of Olympic betting is coming from “in-play” action — wagers made while a game is still in-progress.

“That’s the biggest thing we found during the first weekend,” said Bridge, from Ladbrokes. “Not everyone wants to go down to the shop. People literally sat on their sofas with laptops and mobiles and placed their bets before and during the competitions. It’s their way of feeling like they’re a part of the Olympics, I suppose.”