WPI Economics will produce independent research and analysis of policy challenges across a range of sectors and will be separate from WPI Advisory, set up by Sean Worth and Nick Faith last year, which advises organisations on how to manage political risk.
Oakley was an economist at the Treasury for eight years until 2010 until he became head of economics and social policy at Policy Exchange, where Faith was director of comms at the time.
Oakley was also chief economist and head of financial services policy at Which? until July, and is also a senior researcher with the Social Market Foundation.
His areas of specialism include public sector reform, growth and financial policy as well as tax and welfare issues.
Oakley said: "This is an exciting time to be joining a fast-growing business. With a Spending Review fast approaching, policymakers and businesses need to think radically about how to deliver quality public services in a more productive way. WPI Economics is ideally placed to provide the analysis and insight to make a real impact on policymaking."
Worth described Oakley as one of the most "knowledgeable and well-connected policy experts in the country."