Agencies work for (are paid by) employers looking for employees not candidates looking for jobs.
Lots are crap. Most don�t own a map, I�ve discovered.
Decide what sort of job you want or better skills find a generic job title. Work out what skills you need and have. I�ve employed people for 15 years and I have no idea what a Committee Secretary is. You need to break it down a bit. If it�s administrative or clerical work, say so. If it�s fancier than that, explain why.
Contact an agency who typically source work for companies who employ these skills. Don�t be afraid to phone companies and ask them which agencies they use when they recruit.
Try the links below. I got them by putting public sector jobs into Google.
http://www.publicsectorcareers.org
http://www.totaljobs.com/IndustrySearch/Public SectorServices.aspx
http://www.jobsgopublic.com/
Good luck.
AG