The UK's University of Oxford dropped one place to be ranked as sixth best in the world, meaning Cambridge is the only university in the top five, sharing joint third place with Stanford University in the US.

Oxford was overtaken by the California Institute of Technology, or CALTECH, which soared up from being ranked eighth in 2014. The Massachusetts Institute of Technology was awarded best university by the annual QS World University Rankings, which listed the establishments, closely followed by Harvard University.

Half of the top 10 universities are in the US, while Switzerland's ETH Zurich ranks at number nine. But the UK should not worry, as four of the top 10 universities in the world are here, of which two are in London.

"London is unequivocally the education capital of the world," London mayor Boris Johnson commented. "With four of our universities in the top 40, the city's education sector is going from strength to strength, attracting the world's top talent and producing the next generation of great thinkers and leaders."

The top 20 universities in the world in 2015, based on research by QS:

1 Massachusetts Institute of Technology (MIT), USA
2 Harvard University, USA
3= University of Cambridge, UK
3= Stanford University, USA
5 California Institute of Technology ( CALTECH), USA
6 University of Oxford, UK
7 UCL University London, UK
8 Imperial College London , UK
9 ETH Zurich (Federal Swiss Institute of Technology), Switzerland
10 University of Chicago, USA
11 Princeton University, USA
12 National University of Singapore, Singapore
13 Nanyang Technological University, Singapore
14 École polytechnique fédérale de Lausanne EPFL, Switzerland
15 Yale University, USA
16 Johns Hopkins University, USA
17 Cornell University, USA
18 University of Pennsylvania, USA
19= Australian National University (ANU), Australia
19= King's College London (KCL), UK