Xenia, I've given vouchers some thought, and I don't believe they provide the solution offered by free schools, though they do have the advantage of distancing the education offering from state control.
I'm imagining a scenario where I'm the head of a small independent school. Say I need 16 students paying £7k annually to cover operating costs and salaries. (Of course I'm not talking about well endowed historical schools like an Eton.) If I knew that my parents were each getting a £6k voucher toward fees, and were therefore only needing to pay the £1k top-up, I'd be very very likely to say to myself, hmm, we're really operating on the edge here, and if our enrolment drops below 16 for whatever reason I'd have to let someone go, or another administrative hand in the office would improve our offering greatly, or it be great to be able to offer a sibling discount, etc so why don't I raise tuitions a bit, not a whole lot, but by at least £1k or so. I would do so not because I was trying to bring home more money for myself, but because I would want to shore up or improve the current offering. So I think vouchers would result in an overall tuition rise. Perhaps this is fine, but rather than a £1k top-up, parents would be looking at a £2k top-up, thus reducing the accessibility. And of course, parents on benefits would not be able to address top-ups at all, and there would still be the inaccessibility issue, which free schools address.
On the flip side, vouchers may be the only way to get away from the knee-jerk socialist or PC responses such as "I don't want my tax money going toward . . . IQ selection . . . Islamic schools . . . insert prejudice here." Though if a voucher programme was ever implemented, I suspect there would be a string of caveats about where and how that voucher could be spent.
fivecandles, yes, we can all agree that all schools should be good schools. The difficulty arises in that my definition of a good school is different from yours, as even I suspect mine is different from Xenia's or claig's, even though we all support choice. Take primary for example. A good primary school, to me, is one where the content and methodology are chosen according to a clearly understood child development paradigm, not according to social engineering goals. Let me give an illustration. The Rose report of a few years ago stated that IT training in the primary years was of equal focal importance to that of literacy and numeracy. This statement was made, as Rose himself admitted, to ensure a levelling of access to computers for all children, a social engineering goal, not a pedagogical goal. In fact, such a statement flies in the face of mounting evidence suggesting that computer time for young children is not such a good idea. For me, any school that adhered to the recommendations of this report, or any school who believes watching Disney films is an appropriate use of my dc's school time, is NOT a good school.
If you'd like to maintain that any parent who does not agree with or wants something other than the state mandate should pay for it, that's fine, but understand that that is a political statement.