By Brian Wheeler
Political reporter, BBC News
Fewer people than ever are members of political parties, but growing numbers are only too happy to sign up to single issue campaigns.
From the smallest local protest against a bypass to mass movements such as Make Poverty History or the Countryside Alliance it seems the public has not fallen out of love with politics or activism.
And thanks to the internet, it has never been easier to join or set up a campaign, raise funds and make a splash in the media on a tiny budget.
The growth of 24 hour TV news means there is always a ready market for campaigners' opinions.
Few TV news producers or newspaper editors can resist the combination of good pictures, interviews with "ordinary people" and a handy dossier resulting from a campaign group's detailed research.
Right-wing radicals
By definition the single issue campaigner's stance is normally clear - so they are less likely to have their motives or funding questioned than a professional politician making the same point.
Little wonder that politicians on all sides have been trying to get in on the act.
At one time, activism was largely the preserve of the left - the very word conjours up visions of university campus sit-ins and bearded, placard-waving students marching against the bomb or the Vietnam war.
Some politicians look at campaigners and envy us - our ability to speak the moral and pragmatic truth no matter how uncomfortable that is
Adam Sampson
Shelter chief executive
But since Labour came to power in 1997, what might broadly be termed the right has taken to political activism with a vengeance, through groups such as the anti-Euro No campaign and the Countryside Alliance.
The recently launched I Want a Referendum campaign, although scrupulous to stress it is a cross-party group, is planning to organise a vote on the EU Treaty for half a million voters in marginal seats to put pressure on Prime Minister Gordon Brown, with the enthusiastic support of prospective Conservative candidates.
Other independent groups, such as the Taxpayers Alliance, which receives much of its funding from Tory donors, have been able to make a splash in the media with the sort of message the party leadership can not - or will not - deliver themselves.
A good example was Thursday's newspapers - and this website - which report the Taxpayers' Alliance survey finding that the number of local authority middle managers on £50,000 or more has risen more than nine times in the past 10 years.
Co-option fears
At the other end of the political spectrum, former left wing radicals have gradually found themselves being absorbed into the New Labour establishment.
Many of Labour's high command have their roots in protest movements - the most obvious example being former pensions secretary Peter Hain, who led campaigns against the apartheid regime in the 1970s and helped found the Anti-Nazi League.
Was Make Poverty History co-opted by Labour?
Kirsty Milne, author of Manufacturing Dissent, a study of single issue groups, says: "Gordon Brown still likes to think of himself as a radical. That is one of the differences between the Brown and Blair eras."
But she argues that the era of large-scale mass demonstrations of the type seen during the early years of the Blair era may be over for now, as Brown does not dominate the political scene to the same extent as his predecessor did - and the Conservatives are now stronger, making Labour's opponents feel they have a voice.
There are also concerns among some voluntary groups that the Brown era might see further attempts to co-opt protest movements - through consultation exercises and juicy government contracts - into blunting their attacks or even delivering policy messages by proxy.
"It is plainly a risk for governments of all hues. They are very keen to encourage external voices which are calling for things the government itself wants to do," says Adam Sampson, chief executive of homeless charity Shelter.
"There is a lot of pragmatic advantage for governments to encourage campaign groups to call for change that they are already intending to make, to win political space for them to occupy."
Government pressure
Shelter, which was founded in 1967, on a wave of public outrage following the transmission of Cathy Come Home, a documentary drama about homelessness, pioneered many of the techniques used by today's single issue campaigns.
It now receives about 25% of its funding, about £12m, from the government, mainly in the form of contracts to deliver services such as housing advice lines.
Mr Sampson insists it keeps lobbying and service provision separate, adding that Shelter has been a thorn in the side of ministers on several issues, such as anti-social behaviour orders.
The law is designed to ensure that charities cannot be used by government to act as a front for political parties
Cabinet Office
"The aim it seems to me is to bite them often enough to understand the consequences of not being friendly to you."
But he is also candid about the pressure that can be brought to bear, particularly on smaller, less well known groups, to toe the government line. He cites cases of charities being threatened with a cut in funding by local authorities unless they drop certain campaigns.
Shelter is big enough to resist such crude attempts to silence it, he stresses, but adds: "You do still get informal pressure from individual arms of government."
Envious politicians
There is also a danger, he argues, that politicians are increasingly using charities as "proxies" to speak - and listen - to the public in a way that parties are no longer able to do.
"Some politicians look at campaigners and envy us - our ability to speak the moral and pragmatic truth no matter how uncomfortable that is.
"Trust in politics is at rock bottom, voting levels have never been lower.
"Politicians are looking for ways to engage the public. They are looking for proxies - ways of getting back in touch with public opinion.
"They look at the relationship charities have with their beneficiaries with a certain amount of envy.
"They are increasingly using charities as a proxy."
Party politics
The danger for the charities, he says, is that "over the years we become indistinguishable from the institutions we believe we are in opposition to - there is a danger we may start to lose credibility with the public".
There were concerns in 2005 when Mr Brown and Mr Blair conspicuously allied themselves with the thousands of Make Poverty History campaigners who took to the streets ahead of that year's G8 meeting in Gleneagles.
Cathy Come Home sparked a wave of anger about homelessness
Some within the campaign claimed it been "co-opted" by Labour, arguing that that criticism of Mr Blair's foreign policy had been stifled, although others saw that as a price worth paying for the cancellation of Third World debt.
The government is now the biggest funder of charities in the UK, outstripping individual donations - and it is not unusual for groups who campaign against government policy to receive much of their money from one arm of government or another.
The cash mostly comes in the form of contracts to deliver public services, in a process that began under Margaret Thatcher in the 1980s.
The Cabinet Office is also trying to encourage charities to ramp up their campaigning activities, through its Third Sector review, but it insists it would never attempt to compromise charities' independence or ability to speak out.
"The law is designed to ensure that charities cannot be used by government to act as a front for political parties," says a Cabinet office spokesman.
If groups want charitable status - and the all-important tax-exempt status that comes with it - they must stay out of party politics.
The Charity Commission shortly plans to relax the rules on campaigning - but not, it says, so groups can back particular parties, but so that they are better able to stand up to local and national government and be more vocal in pursuing their aims.
Many politicians remain wary about the influence of single issue campaigns, questioning whether, as unelected and often unaccountable bodies, they can truly represent public opinion.
Growing influence
Labour MP Paul Flynn recently launched an outspoken attack on single issue groups on his widely-read blog, accusing some of "bloated empire-building" and criticised Shelter ignoring good news in favour of carefully-orchestrated "sob-ins".
Attempts by government to open dialogue with groups who vehemently oppose their policies have also had mixed results.
Greenpeace and others walked out of the government consultation exercise on nuclear power, amid concerns they were merely being used to add legitimacy to a decision that had already been made.
But with MPs on all sides casting increasingly envious glances at the public support and credibility enjoyed by single issue campaigns, their influence can only grow stronger