"Afterwards, in one of the slower numbers, the audience replaced lighters aloft with ukuleles aloft which was a strangely poignant sight.With video: Link
"I bet U2 don't have that"
A classical critic's take:
"More than 1,000 people, including Proms director Roger Wright, had brought their own ukes along for a communal performance of the Ode to Joy from Beethoven's Ninth. It sounded curiously Venetian, a bit like a serenade. As a non-uke person, I ended up rather wishing I played one. Tremendous."Link