1971: Agnetha and Björn marry on July 7 in Verum.

1972: Band forms in Stockholm.

1974: Abba celebrate their first No1 single with Waterloo.

1977: First sell-out world tour starts in Europe and ends in Australia.

1978: Benny marries Anni-Frid. 1979: Agnetha and Björn divorce. They have two children.

1981: Benny and Anni-Frid divorce.

1982: Last public performance is screened on Noel Edmonds’ The Late, Late Breakfast Show.

1992: Abba Gold, with hits digitally remastered, is released.

1999: Stage show Mamma Mia!, based on the group’s songs, opens in the West End at the Prince Edward Theatre and becomes a huge worldwide hit.

2000: A man who was deported from Sweden for stalking Agnetha is arrested near her island retreat. 2008: The film version of Mamma Mia! premieres, starring Meryl Streep, Pierce Brosnan, Colin Firth and Julie Walters.

2011: Total sales to date, 375 million records worldwide, makes them the fourth best-selling popular music artists in history.