Take a look at this graph. Whatever it shows (and I'll tell you in a moment), it doesn't look exciting, does it? Something has been pretty much static for the last forty years, with no major sustained swing up or down. All rather flat and uninteresting...
Except for what it is a graph of. It comes from polling carried out by MORI, asking the same question over the years: "How interested would you say you are in politics?" The graph shows how many people gave one of the two positive answers ("very" or "fairly") - and so also shows how the public's interest in politics has been pretty consistent, at a high level. (You can get the full data here.)
Yet follow political coverage about British politics, and you would easily be forgiven for thinking that such as graph would show a consistent long term fall, for the state of politics is usually described as being one of falling public interest. Moreover, turnout in general elections did fall, hitting a low point in 2001 and since recovering - but not to previous levels - which makes this standard picture understandable even if, as the graph shows, it is also wrong.
What has fallen is not the public's interest in politics, but rather the strength of the connection between interest and action in the form of voting. There is a lesson there not only for politicians but for anyone trying to mobilise interest in getting a public policy changed - the public is as interested in politics as it has ever been, as long as you make it about more than simply the question of who to vote for.