In 2010, Hong Kong commemorated the centenary of its railway service. In this context, Hongkong Post issued a set of 6 stamps, each picturing a different model of train, in order to mark this major milestone. The $2.50 stamp featured on this envelope depicts what is called 'tube' in London, or underground railway; it is the most widely used train in Hong Kong.
The 50¢ stamp on the right, which forms part of the 2006 birds definitive issue, portrays a scarlet minivet.
Thanks a lot Trudy for my first cover from HK! (: