When we read about evidence-based policy-making, we're encouraged to believe that the people doing this stuff are carefully sifting the academic literature, testing their ideas against the body of knowledge and exploring new approaches based on this work.
You'd be wrong - they're just phoning a friend:
Unsurprisingly, good relationships and collaborations between researchers and policymakers help research use. This is a common finding—we already knew that policymakers often prefer to get information and advice from friends and colleagues, rather than papers and journals. One consequence is that policymakers may take advice from academics they already know through university or school. In the UK, that tends to mean Oxbridge, LSE, UCL and Kings.
In our everyday lives, we seek advice from friends and colleagues; we don’t trust people who have been wrong before, or who seem to be biased – or with whom we just don’t get along. Exactly the same applies to the process of policymaking and, in our experience, in the process of research collaboration. Negative stereotypes abound on both sides, and our review found that personal experiences, judgments, and values were important factors in whether evidence was used.
Yes folks that thing you thought was evidence-based could well be just as partial as designing policy via an impromptu focus group over lunch in the Dog and Partridge.