As things stand, under the terms of the Northern Ireland Protocol agreed by the UK and EU, it is necessary.
To avoid creating a post-Brexit hard border between Northern Ireland and the Republic – and endangering the Good Friday Agreement – EU goods should be checked when they arrive on the mainland UK.
And so, the Scottish government has just handed a £310,000 contract to US engineering giant Tetra Tech to help find a suitable site. However, the actual construction of the post has been halted until there is “greater clarity from the UK government on the long-term funding, the need for this infrastructure, and more information about the timescales when controls might come into effect”.
The problem is that the UK government has been threatening to invoke Article 16 of the protocol that allows either side to take “safeguarding measures” if they believe the current arrangements are causing serious problems. The UK argues this is within the terms of the recently signed agreement; the EU disagrees.
Whatever the rights or wrongs, the reality is that it risks blowing up into a serious trade dispute with the EU unless calmer heads prevail.
Following the claim by Boris Johnson’s former aide, Dominic Cummings, that the UK government always intended to ditch parts of the Northern Ireland Protocol and that “cheating foreigners is a core part of the job”, ministers need to be working hard to demonstrate this is not the case.
For this is not only about peace in Northern Ireland, and good trading and diplomatic relations with the EU, as vital as both those things are.
At a time when the UK is looking to sign trade deals with as many countries as possible, it is also about Britain’s reputation on the world stage.
The phrase “Perfidious Albion” goes back centuries but has become virtually archaic because successive modern-day governments carefully cultivated good relations with the rest of the world.
If the UK fails to find an acceptable compromise with the EU soon, the uncertainty over a border post may be echoed by uncertainty on a global scale about whether Britain can be trusted. Good reputations are hard to win, but easily lost.