My Lords, whether Article 50 notification is revocable or irrevocable is a matter of policy or law. I believe that we could interrupt the process of leaving the EU only by another referendum. I think this is the point that the noble Lord, Lord Lawson, touched upon. In fact, the noble Baroness, Lady Altmann, made the same point at the beginning of her speech. If in two years’ time Parliament were seen to be blocking the departure of the United Kingdom from the European Union without another referendum, there would be a serious political situation in our country.
While we have talked about conflicts between the Executive and Parliament and between the Executive and the two Houses, I rather agree with the noble Lord, Lord Grocott, that as it stands it should be the House of Commons that has the decisive vote. There is real potential for conflict here. We decided to have a referendum and its outcome can be reversed only with another referendum, which this morning we decided in a sense that we did not want—I admire the Liberal Democrats, who are consistent on this point and who I noticed have their amendment down for Third Reading. At the end of the day, in two years’ time we could be in a very serious, difficult and sensitive political situation. I am not sure the proposed new clause would help handle that.
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The Prime Minister and the Minister in the other place have given a solemn and public undertaking that there will be parliamentary approval for whatever is proposed. I think that that can be trusted and I wonder what the advantage is of putting this proposed new clause in the Bill, particularly as its subsection (4) suggests that Parliament would block the Article 50 process without going back to the people. The referendum was won by only 52% to 48%—that is another conflict that we are handling, I accept that. But it seems that we are not facing up to the fundamental fact of the referendum itself.