Most Eurovision fare over the decades has only been digestible with ironic Wogan chuckles. But 40 years ago in Brighton, four Swedes shot from nowhere, cleaned up and zoomed on to stardom. Yes, Abba mixed bubblegum-pop production with cheese-laden lyrics, but with the twist that they were also seriously musical – with a real harmonic sensibility and an inventive melodic turn. The band reached its apogee several years later with The Winner Takes It All, the unsurpassed breakup song, whose poignancy was redoubled, though both parties denied any connection, by the fact that co-writer Björn Ulvaeus and lead singer Agnetha Fältskog had recently divorced. In true broken-heart style, the song opens with the claim "I don't wanna talk…", before the whole story comes flooding out. Throughout, melancholy piano arpeggios ring like a mournful echo of wedding bells, as the Eurovision winners comfort every loser in love.