The biggest story in music is about to get even bigger? Didn't we just have an event called this? Isn't this event called Apple Expo London?
When the first three international iTunes music stores were ready to roll in mid-June 2004, WWDC was two weeks away. But in this early-Jobs era of Apple, WWDC didn't contain many consumer-oriented announcements. Apple would happily have separate non-developer keynotes the very same month as WWDC, as they did in 1998, 2001, and 2002.
The new online stores were for the United Kingdon, France, and Germany. So it would make sense to have the keynote in one of those countries. The already-planned Apple Expo Paris was still two and half months away. Between the U.K. and Germany, it's not hard to see why they picked the English-speaking country.
London did have a show called MacExpo that ran from 2002 to 2007, and Apple had large booths there, but they never did any keynote presentations. The 2004 MacExpo took place November 18-20, the time of year that Apple generally doesn't make big announcements. (As it so happened, the United Kingdom's first Apple retail store opened on London's Regent Street on November 20.)
Apple crafted an invite for the European press, and ended up mostly recycling the name of their iTunes for Windows event the previous October. Apple started using better, shorter headlines for their music events the following year.
So focused they were this one announcement, Apple released their new music-streaming AirPort Express a week before with a press release, even though Jobs spent some time talking about it during the keynote. Apple didn't want the AirPort Express to be the part of the news story coming out of this event.
With the seal broken on international expansion, future country additions to the iTunes Music Store never garnered more than a quick mention at future keynotes.
In the end, the biggest giveaway that this isn't an "Apple Expo London" keynote is the sound of the audience. You don't get the roar of a crowd of British Apple-fans cheering when Jobs takes the stage. You get a thoroughly polite smattering of applause.