Ms Villiers was attending an event at a youth project in Belfast on Wednesday, but while taking time to talk to local young people, she was also sending out a sharp message to MLAs about the delay.Reforms being introduced by the British Government include a new universal credit payment to replace child tax credit and housing benefit.But the legislation has come to a stalemate at Stormont amid concerns that it could have greater impact in NI due to the amount of people receiving benefits.Sinn Féin and the SDLP have strongly objected to the reforms, arguing that social housing in the region could not cope with those affected by the so-called "bedroom tax".The DUP Social Development Minister Nelson McCausland has insisted he has secured key concessions to address many local concerns about the system."The best way forward here is an agreement across the Northern Ireland parties themselves," Ms Villiers said on Wednesday."That's what devolution is about. That's a better way to get a solution that will stick and will withstand the inevitable pressure that will be placed on it."She continued: "As I say if they want to keep the old system with all its disadvantages that's a matter for them but they will need to fund the difference in cost."As (Finance Minister) Simon Hamilton has made clear to the Assembly the additional costs in keeping the old system could rise to £200m."Devolution involves taking grown up decisions about what system Northern Ireland wants.Theresa VilliersMs Villiers also encouraged politicians to come to a resolution on the Haass proposals on dealing with flags, parades and the past.Former US special envoy Dr Haass and Professor Meghan O'Sullivan were brought in in September by the NI Executive parties to attempt to resolve the contentious issues, but after seven draft proposals an agreement was not reached by the end-of-year deadline.The Secretary of State said the Government would consider any bid for additional Treasury funding to set up new public bodies if proposals go forward, but stressed it could not make any promises.She said that progress on these issues "would boost our efforts to strengthen Northern Ireland economically", "build a more cohesive and shared society" and demonstrate Northern Ireland's politicians' "will" to tackle issues "that might once have been regarded as intractable"."We've made clear that we want the process to succeed," she said."We've also been clear that we're prepared to be part of compromise, even on issues which aren't easy for us such as the creation of new institutions on the past."She added: "But as guarantor of the devolution settlement, what we won't do is seek to impose solutions that do not have the support of Northern Ireland's political leadership."For any set of proposals to work effectively and withstand inevitable pressure in the future, they need be agreed by those who will ultimately have to implement and operate them."And that is the Northern Ireland parties in the Executive and Assembly - not the UK or Irish Governments."