If "Global Britain" means anything, it means we will have different regulations & tariffs than the EU
Which means there *must* be a customs & regulations border, as a check on those differences
But we *cannot* have a border in Ireland
If I can buy chicken burgers cheaper (and with added delicious hormones) on one side of a border than the other, then someone has to check that I'm not nipping over the border, bulk buying, and selling them to my local shops