The brief announcement in Gordon Brown's speech that Labour will provide free home care for elderly people with dementia was a small glimpse of Labour's ambitious plans to transform social care.

Brown's big conference speech was not the time to go into the fine detail of the debate, but perhaps there could have been a little more honesty about the big issues – and the costs – involved.

The facts are stark: at present there are four workers for every person needing care, but demographic trends suggest that soon there will be only three and by the mid-century only two. There are more and more of us, and we are living longer, but often needing more care in the last years of life.

The health secretary, Andy Burnham, rightly identifies the problem with reform of social care. For too long, he told the Labour conference, politicians had ducked reform because the options were tough. The options are tough, and the obvious fact is that to provide adequate social care for all, someone will have to pay.

Labour has already dismissed the idea of its proposed National Care Service being paid for out of general taxation. Instead, it has suggested three options, and has started a national debate on which the public would prefer: either people pay for their own care; or the state pays some and some is funded through a voluntary insurance scheme; or the state compels everyone to take insurance to pay for social care, should they need it.

The third option – a mandatory insurance scheme – currently looks the most likely winner, with people having to pay between £20,000 and £25,000. One idea is that this money could be deducted from a person's estate once they had died, with the poorest paying nothing.

Ministers talk of their plans to reform social care as the next Big Idea, and are delighted that the prime minister told the conference that social care would be centre stage at the time of the next election. Yet a fringe meeting highlighted the difficulties Labour would face in winning this argument.

Dan Wellings, from the polling organisation Ipsos Mori, had some uncomfortable findings for those pushing for reform: two thirds of people wrongly believe that social care will be free for them if and when they need it, just like the NHS; 80% of people think they may need social care at some point; and curiously, half of people questioned don't really know what social care is. It is, of course, any type of care needed by elderly or disabled people that is not strictly medical: help with washing or toileting, help with mobility problems, help with getting meals prepared and so on.

It is, as Burnham said, the biggest unfairness of modern times that some people have access to good care and others to indifferent care or no care at all, depending on where they live or how clever they are at navigating the system. The establishment of a National Care Service would be truly revolutionary, equalling the setting up of the NHS all those years ago. Yet the level of public ignorance about this crucial debate is worrying, and if Labour is to persuade voters of the importance of its plans, it needs to get those facts and figures out there as soon as possible.