The eighteenth annual Eurovision Song Contest, broadcast from the Nouveau Theatre, Luxembourg.
Luxembourg retained their title, winning for a fourth time with Anne Marie David and "Tu te reconnaitras". Only six points separated the top three.
The rule which only allowed countries to perform in one of their national languages was dropped this year meaning some performers sang in English instead.
Several entries provoked controversy including Spanish entry "Eres tu" which was alleged to be a rewritten version of Yugoslavia's entry in 1966. However the song was not disqualified and went on to become a huge hit internationally.
In addition Portugal's entry was seen as being a barely disguised attack on their dictatorship, Sweden's song used the word "breasts" and Ireland had to send over another singer as back-up when it looked as though their performer might pull out at the last minute.
There were also concerns about the threat of terrorism in the wake of the 1972 Munich Olympics, particularly as Israel was competing in Eurovision for the first time. This led to unusually tight security for the contest and audiences members were advised by the floor manager to stay seated when applauding, otherwise they risked being shot by security forces.
This is an anecdote often recalled by legendary UK commentator Terry Wogan, who made his first Eurovision commentary for BBC TV this year (having cut his teeth in '71 and '72 for Radio 2's Eurovision coverage). Wogan would again provide TV commentary in 1978, before taking over duties every year between 1980 and 2008.