I finished my PhD. It was quite a while ago now. You can download a pdf here, or via the University of Southampton. In short, I found that volunteering was associated with a small, positive effect on political activity. However, that relationship is heavily influenced by social class.
Early volunteering seems to be somewhat formative, in that it is associated with higher rates of political activity in middle age. However, that relationship is much stronger for upper and middle class people, and breaks down completely for people from the most working class backgrounds. There’s a circle, but it’s more privileged than it is virtuous.
Secondly, volunteering last year is associated with slightly raised political interest next year, even after heroic attempts are made to ‘net out’ vital explanatory factors such as upbringing and culture. The effect is small, though, and, as for the longer term relationship, analysis suggests that it is highly dependent on social class.
These small, positive effects should not be overstated. They do not offer sufficient evidence to encourage the use of volunteering as a policy tool to improve political engagement.
I also investigated generalised social trust as a potential mediator for the relationship between volunteering and political activity and found no evidence that trust plays an important role.
So there it is. Four years’ work and many, many tears, in one blog post. Read it and weep.