Singaporeans Marlene De Silva, 76, and Penny D'Rozario, 80, received a prize for being the longest married couple - at 55 years - at a World Marriage Day event yesterday outside Ion Orchard. Feb 11 has been designated World Marriage Day by the Worldwide Marriage Encounter movement, with the American movement celebrating its 50th anniversary this year. More than 300 people gathered outside the Orchard Road mall to participate in a flash mob yesterday to mark the occasion.