A fascinating article on whether or not the political environment produces a correlation between union density and social democracy – that might explain why union density in neo conservative or liberal market economies like the USA and the UK continues to fall: http://www.cepr.net/index.php/publications/reports/changes-in-unionization-rates-in-rich-countries-1960-2010
The argument that a left leaning government helps unions grow has not been reflected in the UK – overall membership has been falling consistently since 1997 despite a huge increase in public sector employment. But the commitment of the Labour Party to market economics, privatisation and the anti trade union legislation of the 1980s has damaged the ability of trade unions to develop and grow.
Even relatively progressive measures like the Minimum Wage have reinforced the notion of individual rather than collective rights. The idea that we might need a Labour Government back as a pre-condition of rebuilding is a dangerous one – unions need to devote more resources, more time and more politics to the organising strategies that have emerged from Community Organising and the rank and file movements of the past.
The article is highlighted on the new TUC Organising website
http://strongerunions.org/2011/11/21/introducing-unionreps-action/