Ireland's debut in the contest.
Up to this contest included, there were no rules regarding the language the songs had to be performed in, as it was taken for granted that any country would want to sing in their own native language and that was taken as an unwritten rule. However, Sweden, who had chosen their song originally in Swedish language, decided to perform the song in English in the festival, being the first song ever fully performed in a language not official from the country that was performing it. Criticism and demands of disqualification arose from other countries, but Sweden had done nothing against the rules so they were allowed to perform. However, from the following year 1966, a new rule was established that forced countries to sing each in their official language or languages, only allowing loose words in other languages. This rule would be lifted in 1973, re-established in 1977 and then definitely removed in 1999.