When you tell people you've worked in think tanks, the first question they usually ask is 'how independent are British think tanks?' I tend to give a fairly defensive answer, arguing that they do a pretty good job of maintaining independence, given that the UK doesn't have the sort of endowment culture on which longstanding US think tanks thrive. But I was having this conversation the other day, and struck on the following metaphor which might capture what is distinct about the British case.
Imagine you're throwing a party, and invitations have to be equally split into three factions. Firstly you must invite your grandparents, great uncles and great aunts. Secondly, you must invite your colleagues. And thirdly you must invite the kids who hang around the local park. When they arrive, they inevitably split into their respective groups, and congregate in separate areas of the room. As the host, it's up to you to come up with topics of conversation on which all three groups will engage enthusiastically and frame that conversation in language that all three groups can understand. If any group opts out or feels alienated by the conversation that you introduce, you have failed in your hostly duties. Within those limits, you have complete freedom to take the conversation where you like.
Now substitute 'government, business and media' for 'grandparents, colleagues and kids' (those were not meant as individually equivalent to each other, although...) and you have a sense of how much independence a think tank has in what it says. Does that count as independence? Sort of.