Over the last 50 years increasingly affluent and educated citizens have turned away from traditional forms of mass politics: joining political parties, trade unions and voting in elections.

Analysis of such trends paints a revealing picture of a political system in flux. Non-governmental organisations (NGOs) such as Greenpeace, Shelter and Oxfam, have marketed themselves as an alternative way to pursue politics. People, in turn, have taken up the offer, choosing to support a personalised portfolio of causes and issues. In this sense politics has been privatised.

Now a newly-published book by social historians at the University of Birmingham sheds fresh light on NGOs, revealing how they have made a huge contribution to the British political landscape, emerging as potent form of expert knowledge and political participation.

Led by a new breed of non-party politician, working in collaboration – and often in competition – with Government, NGOs have ‘brought expertise to expertise and, in doing so, have changed the nature of grassroots activism,’ says Professor Matthew Hilton, one of the authors of The Politics of Expertise: How NGOs Shaped Modern Britain.

Using specific case studies of the homelessness, environment and international development sectors, the book demonstrates how politics and political activism have changed over the last half century.

NGOs may be beset by their own problems: their independence from Government, their effectiveness and the true meaning of their relationship with their supporters are all open to question, say the authors; nevertheless, if we are to understand British politics, we need to understand NGOs.

‘Our aim is to offer a challenging new interpretation of politics in contemporary Britain, through an examination of NGOs,’ explains Professor Hilton, Professor of Social History at Birmingham. ‘As affluent citizens have felt marginalised by the increasingly complex nature of many policy solutions, they have made the rational calculation to support NGOs, the professionalism and resources of which make them better able to tackle complex problems.

‘Yet in doing so, support rather than participation becomes the more appropriate way to describe the relationship of the public to NGOs. As voter turnout has declined, membership and trust in NGOs has increased. But NGOs are very different from the classic democratic institutions of political parties and the labour movement.

‘Attracting mass support has provided them with the resources and the legitimacy to speak to power on a bewildering range of issues, yet perhaps the ultimate victors in this new form of politics are the NGOs themselves.’

The Politics of Expertise: Now NGOs Shaped Modern Britain. By Matthew Hilton, James McKay, Nicholas Crowson, & Jean-François Mouhot. Oxford University Press. £35.