The Swedish pop group that made spangled bell bottoms and platform boots big in the 1970s celebrated its 40th anniversary on Monday night with a party at the Tate Modern gallery in London. Here are eight things you need to know about Agnetha Fältskog, Björn Ulvaeus, Benny Andersson, and Anni-Frid Lyngstad, aka Abba.

1. The four-member band are arguably the biggest thing to have come out of the Eurovision song contest. The Swedish group shot to international stardom thanks to their performance of the catchy Waterloo in 1974. They were the first Swedish act to win the contest.

2. Andersson was a successful musician from an early age. At 18, he was part of the Hep Stars, a wildly popular Swedish boy band. Ulvaeus at 18 was also part of another band, The Hootenanny Singers. The duo met when they were travelling with their respective bands, and collaborated on composing songs. When their bands broke up, they joined forces to make an album in 1970. Faltskog, married to Ulvaeus, and Lyngstad, married to Andersson, provided backup vocals for some tracks.

3. The first incarnation of Abba was in the single People Need Love, released under the credit Björn & Benny, Agnetha & Anni-Frid. All the Abba signatures are there: a catchy melody, simple lyrics, vocal harmonies and that lush Abba sound, achieved with ingenuity in the studio by overdubbing and mixing.

4. The name Björn & Benny, Agnetha & Anni-Frid was a bit of a mouthful. So they shortened it to Abba, which also happened to be the name of a fish canning company in Sweden. By the way, Abba Seafood AB is still around and they are famous for their Kalles caviar and pickled herring (http://www.orklafoods.se/english/Our-brands/Abba).

5. The band have sold more than 380 million albums. But superstardom proved a strain on the marriages of the quartet. Ulvaeus and Faltskog broke up in 1979 and Andersson and Lyngstad divorced in 1981. Although the band never officially announced a breakup, they did not perform together after one last appearance on British television in 1982.

6. The Abba revival was sparked in 1992 by British synthpop group Erasure, which released a four-song EP titled Abba-esque. In it, the group covered four Abba tunes: Lay All Your Love On Me, SOS, Take A Chance On Me and Voulez-Vous. The EP went to No. 1 on the British singles chart and stayed there for five weeks.

7. After Erasure, Abba's popularity was sustained in pop culture by two Australian indie films which became hits in 1994: Priscilla Queen Of The Desert and Muriel's Wedding. Both movies featured soundtracks driven by Abba hits.

8. Mamma Mia!, a jukebox musical which stitched together Abba's discography in a simple story about a girl trying to find her father, debuted in London in 1999.

It was an instant hit and was turned into a movie, starring Meryl Streep in 2008.

The trailer can be seen here: