The Women's Institute has published a report arguing that volunteers cannot adequately replace paid staff in libraries. This has been a fraught subject during the library campaigns.
In Brent, we offered to consider having volunteers running our libraries, but made it clear that we still had to make financial savings. Many people assumed that volunteers are just free, but in fact there is growing evidence that is not the case. In Surrey, the Council lost a court case by failing to provide provision for training volunteers. In Oxfordshire, the authority has accepted the need to have a paid co-ordination post. I find it difficult to imagine how you can have a volunteer run solution without some sort of backing like this, and of course that eats into the Council's financial savings on an ongoing basis.
There is also the question of what happens if something goes wrong. Even if you have some kind of document limiting the Council's formal liability, the Council is still likely to be perceived as having an implicit duty to step in. Such an implicit guarantee is hard to quantify. As yet, we haven't seen any volunteer libraries running into these problems, but I shall be very surprised if it doesn't happen before long.
These things are likely to be from the Council's library budget proper, not just money but also staff time and expertise. The WI report emphasises that volunteers don't work without professional support. This suggests that the standalone "Big Society" libraries won't work effectively. Thus, some Councils which have gone down the volunteer route may find that they are actively damaging their staffed library network by draining out resources.
Of course, there is evidence that in Brent volunteers have been a very effective part of improving libraries and the Home Delivery service in particular. I take from that that volunteers can enhance libraries but only as part of a coherent service, not as a financially driven expedient.