Hmmm.... might the UK join the Pan-Euro-Mediterranean convention, as a way of slowly rebuilding its trade relations with the EU.
The PEM allows its members to use inputs from other members (and EU countries) as part of their 'rules of origin' proportion to gain tariff-free access to the EU customs union.
This would reduce some (but by no means all) impediments to current UK to EU exports.... but is pretty tightly focussed so not to alarm rampant Brexiters too much!
It first needs to not alarm the Prime Minister.
@ChrisMayLA6 it does sound like a sensible move given the fluidity of the world at the moment… maybe time for a better thought-through referendum