Oxford beat Cambridge, the U.K.'s richest university, after a change in the survey's methodology put arts, humanities and social sciences on an equal footing with science, Baty said.
"At places like Oxford, where there's a slightly heavier focus on humanities and social sciences than there is at Cambridge, that levelling of the playing field has helped," he said.
The U.K. had the most number of universities in the top 200 after the U.S., with 32.
While the U.K. did "exceptionally well," the "biggest issue is that we're entering into a very uncertain period of major reform, which will have unforeseen consequences," Baty said. Higher tuition fee, spending cuts and new visa restrictions on international students restricting university income will affect U.K. rankings from 2012, he said.
The Netherlands, Germany and Canada followed the U.S. and U.K. as the countries with most universities on the list. ETH Zurich, the Swiss Federal Institute of Technology, was the highest ranked outside of the U.S. and U.K. at 15th position.
The University of Tokyo, in 30th place, was the top-ranked Asian school. Japan has five schools in the top 200, the most of any Asian nation, while Hong Kong has four and China three. Three Taiwanese universities dropped out of the list this year, leaving just one, while India had none.
Top 20 World University Rankings 2011-12:
Institution Country
1. California Institute of Technology U.S.
2. Harvard University U.S.
2. Stanford University U.S.
4. University of Oxford U.K.
5. Princeton University U.S.
6. University of Cambridge U.K.
7. Massachusetts Institute of Technology U.S.
8. Imperial College London U.K.
9. University of Chicago U.S.
10. University of California, Berkeley U.S.
11. Yale University U.S.
12. Columbia University U.S.
13. University of California, Los Angeles U.S.
14. ETH Zurich Switzerland
15. Johns Hopkins University U.S.
16. University of Pennsylvania U.S.
17. University College London U.K.
18. University of Michigan U.S.
19. University of Toronto Canada
20. Cornell University U.S.