“It would not be sensible, however irritating I understand it is going to be to some people, to go into a negotiation with all of our potential negotiating positions, all of the building blocks of a negotition position, spelled out in public – with the costs and benefits and consequences displayed for our interlocutors on the other side of the table to see.  I can promise you that the EU will not be arriving at the negotiations with all the downsides as well as upsides of its different negotiating positions for us to see.”

So said Philip Hammond yesterday during his evidence to the Treasury Select Committee.  He confirmed that the Treasury will be undertaking assessments of those costs and benefits and consequences – it would be surprising were it not to – but his words above cast light on what the Commons should and should not do as next March approaches.  It should go without saying that MPs can and should quiz Ministers about their negotiating plans: that those Ministers should come to the Chamber and before Select Committees and be held to account.

But it is in the nature of a negotiation that Ministers will not be able to say very much beyond the broad aims that have already been outlined.  It would not be in Britain’s interest for the EU institutions and EU countries to sit with their cards close to their chests while ours were displayed for all to see – with, furthermore, MPs engaged in a public debate about which of them should be played in which order, if at all, quarrelling about which suit is trumps (if any) and arguing in some cases for Ministers to send for another pack.

ConservativeHome wishes the Chancellor better luck with his modelling than his predecessor had, since the former conceded to the committee that some of those key Project Fear calculations were wrong – or, as he put it in his rather less direct way: “it is fair to say that [the Treasury modelling] did not take into account some of the mitigations that we would expect to be delivered”.  He said that these have included to date not moving Article 50 in the wake of the referendum and a substantial monetary intervention by the Bank of England in August.

One might have thought that these possibilities were not beyond the imagination of the Treasury at the time.  The same applies to his most substantial point – that the Government is now embarked on a bespoke negotiation.  To quote the Chancellor again: “it’s also clear that we don’t accept that there are only fixed models which we can as it were apply.  This will be a bespoke negotiation with the EU about a bespoke solution, and therefore again the model didn’t capture all of the potential outcomes”.