If the hon. Gentleman will allow me, I must make some progress, because I have to talk about new clause 4, which relates to the divorce bill-the payment or the settlement. The Prime Minister said that the amount would be somewhere between £35 billion and £39 billion. When the Under-Secretary of State for Exiting the European Union, the hon. Member for Fareham, was on “Question Timeâ€, she said that that was absolute nonsense and would never happen, but it turns out that £39 billion equates to over £700 for every adult in the UK. That is how much we are talking about. That is £700 a head for all the men and women in her constituency who voted for her and all those who did not vote. Strangely, that did not feature on the side of the red bus, and the notion of £350 million a week for the NHS has disappeared into thin air. We do not want to catch that particular bus ever again. I am glad that the right hon. Member for Loughborough (Nicky Morgan), who chairs the Treasury Committee, has written to the Comptroller and Auditor General of the National Audit Office to ask him to examine the reasonableness of the sum. The phase 1 agreement said that a methodology had been agreed between the two sides to calculate the sum, but that has not been made available as far as I can see. I hope that the NAO will have that methodology, and that it will go through the agreement with a fine-toothed comb to find the exact figure that our constituents will end up paying. Amendment 39 seeks to tease out what is happening on the question of transition, for which there are all sorts of metaphors. My hon. Friend the Member for Streatham (Chuka Umunna) talked about there being no safe harbour, but the metaphor I like to give is that, if we have a cliff edge, transition is about our having a plank going a few feet out from the cliff edge: it would perhaps give us a bit of extra time, but it would not obviate the precipitousness of the fall that could affect the country-it simply defers when that will happen. The European Union side is absolutely clear that if we are going to have a transition, it will need to be on exactly the same arrangements that we have now, minus having Britain around the table with a say on the rules. That was why I tabled amendment 39. The Government have to get on with securing a transition, and the Chancellor was right to talk about it as a diminishing asset. The arrangements had better be visible and available for businesses to see by the time we get to Easter and the March European Council meeting, because they need to know what will happen. Otherwise, quite naturally, they are going to have to make contingency plans to protect their business thereafter. I was talking to the American Chamber of Commerce to the European Union, which has come up with the sort of transition deal that it believes that many of its firms that work and invest here, employing many of our constituents, want to see. It thinks that a transition needs to have two distinct aspects. First, there needs to be a bridging period during which we can settle all the rules, finish all the negotiations, and establish the treaties and procedure. That will definitely take more than 21 months, and I saw that the chief executive of the EEF was completely scathing yesterday about how little could be achieved in the period currently envisaged. Secondly, there needs to be an adaptation period-a phasing in of the new rules. We need to start getting into exactly what the transition will involve, and that was why I tabled amendment 39. My final point is about new clause 6, on which I will seek the views of the House if I get the opportunity. It relates to what will happen if unforeseen circumstances arise in the process. What will right hon. and hon. Members do if the Government come back with an unacceptable deal? We need to know what our options are. We have asked the Prime Minister on many occasions about the article 50 process. It is a notification process, and she sent the letter in, but when we ask whether the process can be extended, altered or revoked, she says that that is not the Government's policy. That, of course, is not the question we are asking. We are asking whether the process can be extended. What is the legal advice? The Government have obviously taken legal advice, and I suspect that it says that the UK, if it so chose and the circumstances arose, could unilaterally revoke article 50. We would of course have to do that before exit day, because if we chose to do so after exit day, we would be looking to apply to rejoin the EU under article 49, which would mean our losing many of the benefits in our current deal. We in the House of Commons need to know the options available to us.