Rekkers and Kok met during World War II at a munitions factory in Bremen, Germany, where they were working as forced labourers.

[2] Their recording career began in 1950, and they released numerous singles during the decade, the most successful being "Oh wat ben je mooi" which reached #5 in the Dutch charts in 1956.

[4] In a field of 16 contestants, "Katinka" was one of four songs (the others being the entries from Belgium, Spain and Austria) which failed to score.

[5] Nevertheless, "Katinka" proved a success within the Netherlands, and has gone on to become one of the country's better-remembered and recognised Eurovision entries.

[6] The duo never managed to recapture the success of "Oh wat ben je mooi" and "Katinka", and after years of releasing further singles to ever-declining interest, they decided in the mid-1970s to move into music management, their clients including André van Duin, Ben Cramer and Saskia & Serge.