1st warning shot from @DUPleader to @BorisJohnson as he negotiates Schrodinger’s backstop. Any Brexit deal must respect “economic” integrity of whole UK, not just “constitutional” integrity. And any customs border in Irish Sea would impair economic integrity 
@DUPleader @BorisJohnson Another name for this deal could be Cummings's wedge, because its aim may be to seduce English Tory ERG Brexiters to vote for it, in the teeth of unhappiness among Northern Ireland's DUP. And whether by design or accident, so far the ERG seem considerably more upbeat than...
the DUP. The litmus may be Labour's Brexiter unionist Kate Hoey: if the deal ever makes it to parliament for a vote, it will matter whether her Brexit or unionist instincts determine how she votes. And her instincts may be a proxy for whether Johnson's deal passes or flops.
