They received 24 points, which at the time was huge compared to the second place winner, Italy’s Gigliola Cinquetti, who received 18 points.
Olivia, who came fourth, received only 14 points for her entry.
ABBA’s win, and the song Waterloo, saw them soar to the top of the charts in the UK, where they stayed for two weeks.
They also topped the charts all over Europe, of course in their native Sweden, but also in Ireland, Norway, Switzerland and Spain, among other countries.