Under British Rule Singapore started as one of the "Straits Settlements" and became a state of the Malaya Federation. After independence and a period as part of the independent "Federation of Malaya" Singapore broke away as an independent republic. Culturally and ethnically Singapore is mainly Chinese, while Malaysia is mainly Malay and Muslim.
Incidentally the period known as "the emergency" in the 1950s was a revolt by Communists in up-country Malaya who were almost entirely drawn from the minority Chinese population of the other Malay States ( not Singapore ) and consisted mainly of terrorising the majority ethnic Malays.
These stamps were issued during British Rule - each state issued it's own stamps - the other states to a common design and Singapore different. These were in use from 1955 to Independence.
For those who have not been Singapore is well worth a visit - but the humidity is fearsome.
I purchased a Scott album with Strait Settlement stamps and they continue to title pages Strait Settlements well after Malaya Federated States started.
The aircraft shown on the 25 cent stamp has links to three countries other than Singapore. I'm pretty sure it's a Canadian built Canadair North Star which was a modification of the US Douglas DC-4 design with among other changes, Rolls Royce engines. The picture shows an aircraft of the British airline BOAC which called these aircraft Argonaut class. BOAC bought these in 1949 and they continued in long haul service into the 1960s. So the stamp had connections with Singapore, America, Canada and Britain before it was even used.
DannyS is correct. The aircraft is a North Star. For some interesting North Star history, focusing on one of Canada's worst air disasters, see my web page, North Star falling.
A Canadian Pacific Airlines North Star:
The North Star was powered by the same Rolls Royce engine that powered the Spitfire fighter of the Second World War. One of the common complaints about the aircraft was that it was very noisy.
