In 1996 Cambodia issued 4v and a S/S to celebrate the 25th anniversary of Greenpeace.
Greenpeace, well known for its direct action, is an international non-governmental environmental organization which evolved from the peace movement and anti-nuclear protests in Vancouver in the early 1970s. Currently the organization is one of the largest environmental groups with offices in 41 countries worldwide. Its office in Indochina is located in Thailand.
Just like the World Wide Fund for Nature (WWF), Greenpeace authorized a philatelic agency to issue postage stamps for interested countries for publicity. Unfortunately Greenpeace had confrontation with many governments before and eventually Greenstamps, the sole licensee of Greenpeace stamps, found itself mostly receive cold faces when it knocked doors. Till the end of contract only a few nations have Greenpeace stamps and all were issued in the second half of 1990s.
Greenstamps overprinted most S/S for varieties to boost sales, the act has no sign of authorization from relevant postal authorities. The helicopter S/S of Cambodia is in the overprint list, it has two kinds of black pictorial overprints:
They were not sold at the Phnom Penh Central Post Office. This is the original S/S: