Jill Kirby: Now Cameron's opened up clear blue water on welfare, let's see him do the same for families and marriage

The Prime Minister's speech this week on welfare reform was designed to provide a foretaste of the Conservatives' manifesto at the next election. In creating a distinction between coalition policies and those which would require a Conservative majority, David Cameron has set an interesting precedent. By steering into clear blue water, he is giving himself the freedom to talk openly about the constraints of coalition, and to identify the policies which he would like to see implemented but which the Deputy Prime Minister has refused to support. This carries important implications for the conduct of the remaining period of coalition government.

One subject said to be close to the Prime Minister's heart, and on which he and Nick Clegg are known to disagree, is that of family policy. The Conservative leader's long-promised support for marriage through the tax system has been continually postponed, and the Prime Minister has refrained from commenting when his deputy attacks the notion of incentives for marriage. But the new dispensation will surely provide an opportunity for Mr Cameron to firm up on his ideas for promoting family stability, which he can now characterise as a distinctively Conservative ambition.

His speech on Monday made very positive noises about family interdependency, and the need for families to support each other rather than head straight for the benefit office. It would therefore be entirely consistent for Mr Cameron to follow this up with distinctive pledges on marriage and parental commitment. Research shows that a marriage tax allowance would provide more help to less well-off families than further increases in the personal allowance; it would be a natural way for the Prime Minister to carry through his case for encouraging family responsibility.

There's another specific policy which would do much to promote the commitment of both parents and which does not carry a fiscal price tag. It's a policy which recognises the importance of fathers in their children's lives and which would also increase the likelihood that fathers, rather than the benefits office, would take financial responsibility for their offspring. The policy I have in mind is the requirement for both parents to sign their child's birth certificate, so that mothers alone cannot register a birth (save in exceptional circumstances where they can demonstrate that the child's safety would be put at risk by naming the father).

The policy is already set out in legislation drafted by the last Labour government as part of the 2009 Welfare Reform Act, but it has never been implemented. Two weeks ago (on Father's Day), Labour MP David Lammy, who grew up not knowing his own father, called on the Government to implement this important policy, to put in place the assumption that both parents would work together to raise their children. According to the Fatherhood Institute, which has campaigned hard on this issue, 45,000 children in the UK have no father named on their birth certificate. Now that DNA tests are capable of resolving any false claims, and given the safeguards written into the legislation, there is no excuse for denying so many children the right to a father.

Given Mr Clegg's enthusiasm for increasing fathers' involvement in the form of paternity leave, it is hard to see why this policy has remained in abeyance for so long. In response to Mr Lammy's intervention, Downing Street told the Sunday Telegraph that joint registration was an option “being studied”, a surprisingly lukewarm response for a measure that was thoroughly examined under the last government and could be put into law (by order in council) within weeks. From the scant information available, it does appear that the policy has fallen foul of a coalition roadblock: the only minister to go on the record on the subject is Liberal Democrat Children's Minister Sarah Teather, who told the Fatherhood Institute that the government had decided (in 2010) not to proceed with the policy.

If he wants to show a serious intention to get fathers back into the heart of family life, David Cameron should speak out on this subject, or at the very least invite Miss Teather's boss, Michael Gove, to do so. As the Fatherhood Institute explains: “even very small shifts in expectations of vulnerable fathers can lead to quite remarkable positive changes on their part. A trial in the USA showed that when midwives simply learned and used the names of fathers in vulnerable families, this correlated with them paying more child support. Changes in expectation are highly effective and the change in birth registration would be a game changer in some families. It would also place a duty on all professionals to inform parents about the expectation, so catalysing more substantial engagement with fathers.”

Leadership on this subject is vital, and Conservative silence has been disappointing. In the past, when Conservatives have sometimes struggled to find the right message about marriage, endorsing the importance of fatherhood has provided opportunities to build a broad base of support. Today, speaking out for father involvement would show that the Conservative view of welfare is not just about fairness, or saving money, but also about the emotional and developmental needs of the child.

Here we have a ready-to-go measure which promotes family responsibility, sends out all the right signals on welfare and is being urged by one of the most constructive and thoughtful figures on Labour benches. Indeed, it could be implemented without the support of the Liberal Democrats, should they wish to distance themselves from it. In other words, it's a distinctive policy David Cameron can offer which does not even have to be postponed to a future Parliament: clear blue water right here, right now.