I remember reading an article by Ben Goldacre written shortly after the referendum, maybe 2017ish after A50 was triggered. He was reassuring the reader that Brexit would not and could not happen. His reasoning was that if was going to happen, the UK would need to have already begun construction of the necessary border infrastructure and training of additional staff. Since there was no evidence of construction activity at the ports and no staff recruitment going on, none of this was happening and Brexit, particularly a hard Brexit requiring additional border checks was literally impossible.
Shows what he knows, and to think they made him a professor.