The noble Lord identifies the important characteristic of the OBR, which is its statutory independence. That is a strength and something we all commend. In response to the noble Baroness, Lady Kramer, we have to respect what the OBR by statute is required to do, and we expect it to do that.
There are practical difficulties in addition to those which I was just beginning to outline when the noble Baroness made her intervention. If the Government agreed to have a forecast ahead of the withdrawal legislation being considered by Parliament, there is simply no guarantee the OBR would be able to take the terms of the agreement into account in its forecast. For example, if there was only a short period of time between the agreement being made public and the point at which legislation is introduced, then the OBR may not have capacity to conduct a thorough analysis.