Many of the world’s regions have switched places in the UBS rankings as currencies fluctuated in the wake of the financial crisis.

UBS Bank used to rank London the most expensive city in the world - but it has now plummeted to the 22nd spot. All in just one year.

In the 2009 list, Oslo has been crowned the most expensive city in the world, followed by Zurich and Copenhagen.

Mercer has just released its top 50 most expensive cities in the world based on cost of living.

Mercer’s Worldwide Cost of Living Survey 2008 is used to help multinational companies and governments determine living costs for their expatriate employees, who usually demand a relatively high quality of life.

Mercer’s survey covers 253 cities across six continents and measured the relative cost of over 200 items in each place, including housing, transport, food, clothing, household goods and entertainment.