It comes as Transport Minister Norman Baker outlined plans to devolve decision-making on major local transport schemes to local transport bodies from 2015.
He was followed by his Labour shadow, Owen Smith, who questioned Mr Jones's previous suggestion that the Treasury would have the final say on whether to devolve taxes.
Gordon Brown's assertion on a recent trip to Belfast that it was time to devolve policing and justice pleased Sinn Fein, who were promised the move by Tony Blair.
Mr Cameron agreed, but said the legal position on the referendum had to be clarified first, adding that the UK government had offered to devolve powers to the Scottish parliament to resolve the issue.