Royal Albert Hall in London hosted the 13th Eurovision song contest on April 6, 1968. That year Eurovision was broadcasted in color for the very first time! Strangely there were no new countries debuting, no countries withdrawing nor returning.
Spanish Massiel ended winning with La la la. There have been talk about vote rigging ever since. Spanish dictator Franco would have bought votes all over Europe and thus finished above UK's own Cliff Richard by one vote. One should remember also that Massiel was not to sing the song originally but Joan Manuel Serrat. He insisted on singing it in Catalan, and was replaced by Franco's regime.
After winning Massiel released the song in four languages, and quite a few cover versions were made in other languages. She continued her career until mid 1990's and have done some occasional recordings even after her retirement announcement in 1996, like this remake of La la la
As said, Cliff Richard came second with evergreen Congratulations, while Eurovision 1962 winner Isabelle Aubret finished third for France with La source.