Nearly half the Dutch population does not know the words to the Wilhelmus, the Netherlands’ national anthem, according to research by train provider NS.

Why the NS carried out the survey is unclear, but the results show that 40% of the Dutch do not know the words, not even to the first of the 15 couplets.

However, 73% think the Wilhelmus is important and would like to sing along at important events such as King’s Day or the World Cup in Brazil later this month.

Not knowing the words, the Dutch either hum along or make up the words they think are part of the text, free newspaper Metro reports.

The Wilhelmus is the world’s oldest national anthem and tells of the life of William of Orange and of his fight against the King of Spain for independence. It is written in the first person as if it were sung by William himself. This necessitates singing line such as ‘I am of German blood’.

The NS will set up large screens at main railway stations during World Cup so that passengers will not have to miss any of the football action.