SAN FRANCISCO — When Timothy D. Cook, Apple’s chief executive, presents an updated iPhone and other gadgets at an event on Wednesday, several hundred of the company’s invited guests will be seated in a giant auditorium in San Francisco to watch.

More than 5,000 miles away in Britain, members of the London Mac User Group — comprising about 90 people, many of whom are longtime Apple enthusiasts — will also be watching Mr. Cook’s event closely, but via a live stream at a pub called the Sun Tavern. Along with bar snacks and pints, a bingo game and a raffle will be part of the fun. The top prize: an Apple accessory.

“We organize a ‘keynote bingo’ for all of the catchphrases we think will come up,” said Paul Foster, 46, vice chairman of the group, which is known as L.M.U.G. While the group usually holds such gatherings at a nightclub called Tiger Tiger, that venue is closed for remodeling. The club also normally meets earlier in the day, Mr. Foster said, because “we have people of many ages, but we also have a lot of retirees.”

So it goes these days for many Mac user groups, which were once the backbone of Apple’s faithful. Beginning in the late 1970s to troubleshoot and discuss Apple products, these user groups are now mostly sidelined — to pubs like the Sun Tavern, church basements and libraries — as the company has outgrown them to become the world’s most valuable enterprise, selling tens of millions of smartphones and tablets every quarter.