I already said upthread that I'm generally in favour of vaccination, although we spread them out now and say 'no thanks' to things like rotavirus and the flu spray. I have to agree though that enforced vaccination is ethically indefensible, because you are forcing a person, usually a baby, to undergo a medical procedure that carries risks which cannot be absolutely known ahead of time. By the time a child has had a bad reaction, the damage is done.
There are also many other issues that have been touched on in this thread, such as the fact that most susceptible people are actually adults (which has a massive impact in herd immunity), vaccines wear off more quickly than disease-mediated immunity in general (see the current problems with Mumps), and that the medical profession is often reluctant to link problems with vaccines, at least 'officially'. (This same phenomenon has been in the news recently with mesh implants, with many patients being told their chronic pain couldn't possibly be related to the implants - if medics won't acknowledge the link you cannot possibly gather accurate statistics about the levels of side effects and therefore risks of a procedure).
There is also an entire field into non-specific vaccine reactions, published in peer reviewed journals, which indicates that vaccines impact the immune system in a wider sense than providing protection against a particular disease. Sometimes this is for the better, sometimes it weakens the immune system, but it seems that the schedule (the order they're given and what's given together) probably also affects the immune system in general. This isn't currently considered in our schedule at all, which is decided primarily around logistical issues.
The UK, without compulsory vaccination, also has some of the best vaccine coverage in the world with uptakes routinely very high. People do in general trust what the NHS tells them. Eroding that trust by setting up conflict is risky. Rates are actually lower in places with compulsory vaccination, perhaps because vaccines are scrutinised more carefully in these contexts.
For all of these reasons I think compulsory vaccination would be a mistake, and I'd be horrified if I was forced to give my baby a treatment that I didn't believe was in their best interests (and not all vaccines are on the schedule to protect children from killer diseases - some are for the protection of others, some are about reducing costs to the NHS).