The Secretary of State said that it was binding so far as he was concerned. That is not the same as a legal commitment, and Secretaries of State and Governments can change. That is why we need a commitment on the face of the Bill.
Let me fast forward to the second amendment. If there is really no problem with proposed subsections (1), (2) and (3), why not accept them along with proposed subsection (4) and put them on the face of the Bill? This is becoming an obsession with having a clean Bill: “Our Bill must not be amended, even when it is proper, right and decent to do so.”