Netherlands' Crown Prince Willem Alexander and Princess Maxima are seen arriving at Westminster Abbey before the wedding of Britain's Prince William and Kate Middleton in central London on this April 29, 2011 file photo. Queen Beatrix, who turns 75 on Thursday, announced she was abdicating in favour of her son, Prince Willem-Alexander, who will become king on April 30, 2013.     REUTERS/Toby Melville/Files   (NETHERLANDS  - Tags: ROYALS POLITICS)