What's the world's most expensive city?

Is it London, playground of the world's super-rich, or an Asian financial centre such as Hong Kong or Singapore? In fact, two of the most respected surveys locate the world's most expensive city in Africa

Where is the world's most expensive city? London, where garages can sell for half a million pounds? Or Paris, where hotels, restaurants and boutiques cater to almost 50 million tourists a year in the world's most visited city?

The answer, according to Mercer's annual Cost of Living survey, might not be what you would expect: the consultancy puts Luanda, in Angola, in first place in its 2015 survey of how expensive 200 world cities are for expatriate employees. A pair of jeans apparently costs in excess of $240, and a basic fast-food meal will set you back $18.95 - in a sub-Saharan country where millions get by on less than $2 a day, and which the World Bank rates as the seventh worst in the world for income equality.

Related: Where is the world's hottest city?