ABBA stars Bajran Alvius and Benny Anderson arrived in London yesterday before the start of the band’s return.
Björn, 76, and Benny, 74, Agnetha Fältskog, 71, and Anni-Frid Lyngstad, 75, have not performed since 1982.
But fans can see them announcing new music on their official YouTube channel at 5.45pm in addition to the stage show ABBA Voyage.
A source said: “Bjorn and Benny arrived in London as a surprise for fans at the event and live stream.
“They will show everything about new music and their stage shows.”
Suraj revealed that the group was returning last week, 39 years after announcing its break in 1982.