Alex Stevens, a professor from the University of Kent, took six months out of academia to work in the Whitehall policy machine. He learned that Whitehall is a policy-making machine that prefers certainty to accuracy, action to contradiction, and only accepts ‘evidence’ that fits the story already being told. Policy is based on systematic distortion of evidence.

See his article here.

He has also published this as a longer academic paper here:

Stevens, A 2011 ‘Telling policy stories: An ethnographic study of the use of evidence in policy-making in the UK’ Journal of Social Policy, 40 (2). pp. 237-256.