Note: The Press Association gives a date of 25 April 1974
I suspect that the date of 25 April 1974 is infact the date the photos where released to various news agencies around the world including the UK's Press Association and that the date of the 30 March 1974 was the actual date Lena Zavaroni visited The Madurodam Miniature City, South-Holland, The Hague.
The Nationaal Archief is the national archives of the Netherlands, located in The Hague. The date of the 30 March 1974 is the date given on their website.
Fanz of Lena Zavaroni (Robcamstone)