A painted Boris Johnson is right twice a day

From the Daily Mail:

Under the [customs] partnership, officials would track shipments into the UK and collect tariffs for Brussels on goods ending up in the EU. Mr Johnson said this would simply lead to more red tape.

"It’s totally untried and would make it very, very difficult to do free trade deals," he added, "If you have the new customs partnership, you have a crazy system whereby you end up collecting the tariffs on behalf of the EU at the UK frontier.

"If the EU decides to impose punitive tariffs on something the UK wants to bring in cheaply there’s nothing you can do...

"That’s not taking back control of your trade policy, it’s not taking back control of your laws, it’s not taking back control of your borders and it’s actually not taking back control of your money either, because tariffs would get paid centrally back to Brussels."

If you think about it, it is indeed a really stupid idea that will make things more complicated, not simpler. As he says, if the EU wants to tax imports, that's for them to sort out. And in turn, we can set our own tariffs (preferably at zero, but that's another debate) on things we import.

In any event, EU member states and the UK, like most countries, have the concept of customs-free transit. So if goods from Country X are taken off the boat here and put straight onto another boat to Country Y, they are not subject to any UK tariffs and Country Y just treats those goods as if they had arrived directly from country X. Which would sort out most of the perceived problem.