The state funeral will be held next week, probably on Tuesday or Wednesday. He will be buried in the royal family grave in Delft. They're already mobilizing police and putting up road blocks! Since Prince Claus is the first Royal person to have died for 40 years, nobody really knows what to expect, although I don't think the funeral will be as big as the one your Queen mother got...
There will not be a day of national mourning, it's up to every shop and company itself whether they'll close or stay open on the day of the funeral. (I think this might have to do with the fact that Prince Claus always wanted to break free and not follow protocol. Once while giving a speech, he took off his tie and throw it away! With Claus dead everybody fears that the Queen, who was much less formal thanks to her husband, will loose that again...)
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The cost of living has not affected its popularity - Loesje