To expand a bit on the above, the big problem for Ireland is not so much the Tory government or the EU negotiators as much as it is the DUP.

The DUP’s red line is no internal UK customs regime (even if it’s a win-win)

If the Tories were not in coalition with the DUP I think they would be quite open to having the customs border in the Irish Sea, but that’s a bit unlikely with May dependent on the DUP in Westminster, unless she is willing to risk her government collapsing as the DUP bolt.

That’s part of the reason the Irish government is being so intransient at the moment in my view, as they know they have to counter the influence of the DUP on the British government.