Budget Responsibility and National Audit Bill [HL]

My earlier question came from reading the evidence of Professor Wren-Lewis to the Select Committee. He considered that if, "““the Treasury decides that the OBR model is wrong in some sense, I think basically then it is up to the Treasury to decide whether it wants to move to an alternative model or an alternative way of doing things whereby it produces its own forecast and does not rely on the OBR””." I understand that the Government accepted that when they responded to the Treasury Committee. That was what prompted my earlier question.