I’ve been talking to Conservative MPs about the so-called divorce bill, or more accurately the United Kingdom’s outstanding liabilities to the European Union.

There are two untrue memes floating around about the “divorce bill”: the more long-running one is from Leavers, that the UK is “paying to leave”. The British government is being asked to pay for spending commitments agreed to while we were members but where the bill will come in after we leave.

The second, which is more recent, is coming from Remain politicians: they are describing it as an additional cost of Brexit. Actually this so-called “divorce bill” would have been paid by the UK regardless of whether we had stayed in the EU or not. Effectively, the “divorce bill” is like paying for your share of a meal out. Whether you leave money because you are leaving early, or pay with everyone else when the bill arrives, the amount does not change.

The problem the government has is that these two memes – which are, I suppose, really the same meme with a Remain or Leave accent – have been widely bought into by Conservative MPs. What they are mostly saying, with the exception of a handful of ultras, is that they are happy to pay provided the final trade deal is worth the price. Provided the result is a trade deal that secures a good standard of access to European markets, the bill is acceptable to most Conservative MPs.

But the matter of the UK’s outstanding liabilities and the quality of the resulting trade deal are entirely separate. The question of the divorce bill is being folded into exit talks because, of course, once we’ve left, there is no real mechanism for the EU to compel payment of these outstanding liabilities. Its leverage to secure the United Kingdom’s tab is dependent on not moving onto the trade talks first. (To continue the restaurant analogy, if I refuse to call a cab for you until you give me the money for your food, you are not guaranteeing that the taxi home will be reliable or quick and you still need to pay the cab fare.)

The other headache for the government is that there is not a great deal of understanding at Westminster that the demands of the government’s Brexit strategy and indeed the wishes of pro-Brexit MPs – the United Kingdom out of the customs union and single market, free of the regulatory orbit of the EU – means that the United Kingdom and the European Union will have significantly reduced access to one another’s markets.

Indeed, this is sort of the point of Brexit. The United Kingdom sacrifices a level of access to EU markets in order to gain a greater deal of political freedom. That’s the trade-off that the UK made in voting to leave. I should note that some Conservative MPs, both Remain and Leave, very much do understand that this was the trade-off they made, as do opposition Remainers on the whole.

But the troubling question both for Theresa May, and more worryingly for the prospect of any deal, clearing the House of Commons is that many Conservative MPs and the pro-Brexit press don’t seem to have grasped this yet. A Canada-style deal ought to be hailed as the success of the Brexit project. May’s nightmare is that it may be seen as a failure.