Labour leader Ed Miliband and his brother David both gave speeches under the same roof on Tuesday night - in separate rooms.
The Labour Party leader addressed a gathering of celebrities and activists in the East Room on the top floor of the gallery.
Earlier in the evening former foreign secretary David Miliband was in Tate Modern's Starr Auditorium to take part in a panel discussion about global forums like the G8 and G20.
At 10pm on Tuesday night the riverside facade of Tate Modern provided the backdrop for a series of projections recounting the history of protest songs in a half-hour montage of images, films, words and songs.
The 10pm show is due to be repeated on Wednesday and Thursday night.