Having bought a Macbook during during my internship stint in the USA, I've always been powering it using a power extension cable which has a USA type plug. This meant that I always had to use a travel adapter. Thankfully, over the weekend I found a spare UK type plug lying around the house and decided that it was time to get the original cable plug replaced.
Stripping the cord exposed wires of 3 colours - green, white and black - which are of the NEC (US National Electrical Code) standard. Green gets connected to earth, white to neutral and black to live. Here in sunny Singapore we follow the IEC (International Electrotechnical Commission) standard where a green-yellow wire gets connected to earth, blue to neutral and brown to live. You can learn more about wiring colour codes here.
After replacing the cable plug, I was finally able to power my Mac without the need for a travel adapter.