The thrills of Super Bowl XVII made a transatlantic leap Sunday night as British television devoted nearly five hours to the American extravanganza, broadcasting the game live to a national audience for the first time.

It was almost 3 a.m. locally when the host, Nicky Horne, a diminutive London disc jockey and football aficionado, closed out the night of the Washington Redskins' victory over the Miami Dolphins. How many British television sets were still tuned in won't be known for a week or so, but the broadcast completed a season when U.S. football rivalries secured a place in British life.

Every Sunday evening since the players union strike against the NFL ended, Britain's new commercial station, known nationally as Channel 4, has shown an hour of U.S. football highlights in prime time, featuring edited versions of a professional game of the week. The program, said producer Elaine Rosen, earned Channel 4's highest viewing figures for its day, with an audience estimated as high as 2 million. More than 20,000 people wrote in for leaflets on rules of the game or to predict the eventual championship teams, she said.

To make the action and commentary from the American feed understandable to the uninitiated British, Horne would ask questions of Miles Aiken, a former basketball player in the U.S. with a gift for easy explanations. For the Super Bowl, Aiken flew to Pasadena, Calif., and provided British viewers with a personalized supplement to NBC's play by play while Horne in the studio bantered with British-born kicker John Smith of the New England Patriots.

Also on hand was a London bookmaker who reported that the equivalent of about $40,000 was bet on the contest in his establishment alone, with Miami slightly favored. The Channel 4 team also agreed in pregame talk that Miami would win, an observation similar to NBC's crew of experts.

But the Redskins were clear favorites among the crowd at Sundance Studios, a London health club that--recognizing the chance for a gala party--offered a big screen telecast of the game plus a slice of pizza, a hot dog and three cans of beer to fans paying five pounds (about $8). Some 150 people turned out, a British and American mix that Simon Ludgate, one of the organizers, dubbed "Yankophiles."

They were, on the whole, a cheerful bunch. Wearing a well-washed Redskins jersey and cheering lustily was Jeremy Molek, 20, a student at London's Imperial College who said that although his time in Washington had been short, his devotion to its football team is considerable. John Adamson, 23, from McLean Va., who is also studying in London, said proudly that he had been at RFK Stadium for the Redskins-Vikings game on Jan. 15.

But Pete Thomas, an insurance broker from New York, intently introducing football to his friend, Lorna McKinnon, on a small set in a quiet corner of the club, confessed that watching the game made him "very homesick."

To British fans, according to Andrew Moor, a social worker who returned home last year after 12 years in the U.S., American football has "the glamor that soccer here has lost." There is the razzamatazz of bands and cheerleaders, he explained, the massive crowds and, of course, the excitement of the game.

British soccer (confusingly known here as football) still draws the country's largest sports crowds. But it has suffered considerably in recent years from falling attendance and revenues, largely blamed on regular outbreaks of postgame violence by rampaging spectators.

"A lot of people here tend to think of America as a violent and frightening place in a lot of ways," said Rosen, who came to Channel 4 from the BBC's sports department. "But when I went to my first football game in the U.S., I'd never felt so secure in all my life. That is the reverse of what is happening in Britain where football violence is getting worse."

In U.S.-style football, as is the case with rugby, another fan said, the mayhem is on the field.

Given the audience figures, Channel 4 is plainly creating a new audience for American football and the series will definitely be back next year. The advent of Sunday night television, Clem Thomas in the London Sunday Observer wrote this week, "has bred, if nothing else, a new addiction among those who like their sport raw and physical."