The government's Brexit negotiating position is ambitious - how would the British public feel if the EU offered the UK less favourable terms?
With the Queen now having given Royal Assent to the Article 50 Bill, the UK is on the verge of starting negotiations to withdraw from the European Union.
After Theresa May's Brexit speech in January we asked the public what they thought of her negotiation aims and, on the whole, they gave them the thumbs up. This week we asked again and found respondents were still on board with the Prime Minister's position on Brexit. By 52% to 22% people think it would be good for Britain, 61% they think it would respect the result of the referendum, by 49% to 25% people would be pleased at such an outcome.
While this is all well and good, the rosy picture for the government painted by these figures assumes that Theresa May actually achieves the sort of Brexit she wants.
While on balance the public think Theresa May's ambitions are possible (41% think they are realistic aims, 33% don't), some of the targets she has set herself are very difficult: a free trade deal that doesn't involve freedom of movement with the EU, leaving the customs union but not facing full customs checks, not being in the customs union but having an open border with Ireland.
But how would the public react if she failed to deliver? To see, we asked a second bank of questions. We asked people what they would think if Britain ended up with a far less favourable version of Brexit, a hypothetical Brexit where Theresa May doesn't manage to get some of things she wants.
We assumed that there would be a deal on preserving the existing rights for EU living in Britain, and British citizens living in the EU and that Britain and the EU would continue to co-operate on security matters. However, in this version of Brexit there is no deal on customs, meaning customs checks for British imports and exports, there is only a limited free trade deal between Britain and the EU, meaning tariffs on many goods and services, and there are border checks with the Republic of Ireland.
By 40% to 30% people think this version of Brexit would be bad for the country, and only 29% say they would be happy with the outcome. Asked what should happen next, the most popular answer was - predictably - to go back and try and get a better deal.
But if a better deal wasn't available and people were forced to choose, 41% said Britain should go ahead and leave on those terms, 32% think there should be a referendum on whether to stay in the EU after all, 27% of people are unsure.
Right now, we don't know what the circumstances would actually be. We don't know if other EU countries would agree to Britain going back to renegotiate the deal. We don't know if Britain could change its mind, withdraw its Article 50 notification and stay after all. It may be that these questions are meaningless if it wouldn't actually be possible.
These figures do suggest there is some room for optimism for both sides. For Leavers, the research suggests that more people would want to stick with the country's decision and leave even if Brexit negotiations are disappointing. For those who would like Britain to stay after all, the 27% unsure of what they would favour in those circumstances does hint that opinion might change if negotiations go badly enough.
Anthony Wells is YouGov's Director in the Political and Social Research Team
This blog first appeared on the YouGov site, and can be read here