Virtuoso Chinese pianist Lang Lang joined the celebrations at the Last Night of the Proms, the culmination of the world's largest classical music festival and a unique celebration of Britishness.
The BBC promenade concerts, a series of more than 180 shows over two months, date back to 1895.
The famous Last Night of the Proms is a raucous sing-along of patriotic tunes including "Land of Hope and Glory", "Rule, Britannia!" and "Jerusalem".
Some critics object to the flag-waving bash as jingoistic and out of touch with modern-day, multicultural Britain.
But the thousands of people clutching their Union Jacks on Saturday were revelling in the enduring celebration of national pride.
"It's a fantastic atmosphere, all people of all nations celebrating the joy of music," said Paul Jenkins, 57, an accountant from Watford outside London.
"It's one of the few times that we can sing national songs and fly the Union Jack."
This year's season season attracted record audiences.
More than 300,000 people attended the concerts, 94 percent of tickets were sold for the main evening events and 52 of the 74 concerts in the Royal Albert Hall sold out entirely.
Although the focus is on the music, it can turn political.
Saturday night however was all about celebration.
Balloons whizzed through the air, as bunting and British flags draped all around the 19th-century red and gold hall, though dozens of international flags were also being waved with pride.
And while the choir and orchestra were formally dressed in black tie or evening gowns, audience, known as prommers, wore glittery bowler hats, Viking helmets, Union Jack ties and waistcoats.
And contrary to normal concert hall tradition, they drank copious amounts of wine throughout the evening's performances.
"The audience is so attentive, and with the prommers standing it's a little like being at a rock concert," the 29-year-old pianist said.
But it is the raucous second half that prommers come for and millions watch live on television.
Tens of thousands also gathered in nearby Hyde Park for an open-air Proms, and they joined in the finale with a live feed from inside the Royal Albert Hall.
Conductor Edward Gardner told the crowd: "With your voiciferous, passionate, sometimes unruly support, you've really guaranteed the Proms remain a cornerstone of our cultural identity in this country."
With even the orchestra firing off party poppers and the stage covered in streamers, the crowd rose to their feet, grabbing hold of each other and belting out "Land of Hope and Glory".
English soprano Susan Bullock reappeared in a spectacularly over-the-top Britannia costume for "Rule, Britannia!", and valiantly soldiered on even though her winged hat kept slipping off.
One singer from the chorus joked afterwards that it aptly symbolised Britain's declining power in the world.
After "Jerusalem", the concert finished with the national anthem "God Save the Queen", then a crowd rendition of "Auld Lang Syne", a Scottish tune normally reserved to see in the New Year, where people cross arms and hold hands as they sing.
Source: AFP Global Edition