When you are conducting a negotiation, as leading Conservative and Labour figures are now doing over Brexit, it is essential to understand what the people on the other side of the table really want. For instance, in the talks that led to the Coalition Government in 2010, we soon worked out what the Liberal Democrats wanted most. Apart from getting their hands on ministerial red boxes for the first time in their lives, they wanted a change in the voting system so that they might be in office almost permanently.

So we gave them enough of a chance to change the system for them to want a deal, but not enough to guarantee the outcome they had in mind, and in the end the electorate put paid to their ambitions in a referendum. The negotiations worked, and the coalition was created, because we understood what they wanted most and gave them a shot at it.

Now think what it is that the Tory and Labour leaderships really want from the effort to find a jointly acceptable solution to the Brexit conundrum. For the Cabinet, this is a negotiation they have been forced into by the refusal of a small section of their own party to pass the deal on the table. They genuinely want to solve the problem threatening to overwhelm the Conservative Party and the entire body politic, but their room for manoeuvre without bringing themselves down is very limited.