In his keynote speech, Mr Cameron told delegates, 'Families matter because almost every social problem comes down to family stability. And so I will set a simple test for all of our policies: does it help families?'
He said many families in Britain were 'trapped in poverty' because childcare remained 'costly and complicated'.
Financial help for parents should not just be limited to formal childcare, he said, acknowledging that extra help with childcare was 'particularly vital' for single parents.
Mr Cameron said, 'Britain has got the most expensive childcare in Europe.
So we support the Government's efforts to put more money into childcare.
But why are they saying you should only get help if you use formal childcare? What about the grandparents, the friends, the neighbours?'
Both Mr Cameron and Mr Osborne are said to be considering the idea of creating a transferable tax allowance between parents, so that one can pass on the tax benefit to the other if they stay at home to look after their children.
Earlier in the week Mr Osborne visited Talbot Day Nursery at Bournemouth University. He told party delegates that he would help parents with childcare and extend flexible working for parents.
He said, 'I know there may be a few who think that childcare is something to be discussed in mothers' groups, not on conference floors, or that equal pay for women should not get equal billing. Well, we in this hall think they're wrong. These issues go to the heart of what it means to be a civilised society.'
