Back in 2003-04, David Peetz and Barbara Pocock (from Griffith University and the University of Adelaide) conducted a survey of 2500 union delegates to examine the power of workers in their workplace. You can download the paper here (pdf).

The paper on the report is definitely worth reading and at 11 pages (many of which are graphs), you can do it fairly quickly.

What I took out of it is this:

Local power was stronger where:

• unions were democratically organised;
• delegates were confident, active, had clear roles and had strong networks of support at the workplace and with the union office, particularly through the organiser;
• unions promoted common identity through inclusive policies than took seriously women’s issues;
• the employer (and the delegates’ supervisor) were supportive of the union delegate’s role; and
• where job security was not declining.

Training indirectly helped strengthen local power. Employer-related factors were only one eighth as important as union-related factors.

All of which stands to reason, and definitely accords with my experience. The key is that delegates are central to union power in the workplace.