The campaign by Brexiteers and the British government against the Northern Ireland backstop has been sustained for up to two years with claims that they have a viable alternative that can do everything required of the backstop itself.

It goes by the name of “alternative arrangements” and consists in a collection of technological and administrative fixes that would supposedly do away with the need for controls on the Border.

The Government and the European Commission have insisted that any proposals they have seen are either completely inadequate and insufficiently secure or technologically unproven.

Now a secret, internal British paper by officials preparing the UK negotiating position admits as much. But “it doesn’t tell us anything that we don’t know and haven’t been saying about so-called alternative arrangements for a couple of years”, one commission official close to the talks says bluntly.

The report, which is marked “official-sensitive” and has been prepared for the UK’s EU Exit Negotiations Board, is dated August.

It looks at the challenges involved on the Border in a no-deal situation and summarises the work of multiple subcommittees and the NI Department of Agriculture Environment and Rural Affairs (DAERA) in assessing a variety of “alternative arrangements” (also referred to as “facilitations”) as a basis for preparation of a UK negotiating position.

The report’s authors warn that it should not be released – “we and other departments have cautioned against this given the potential negative impacts on the renegotiation with the EU and we understand No 10 are in agreement . . . ”

The “concerns” are technical capacity (much is beyond available technology), the administrative burden (particularly on small business), and political.

Small businesses Small businesses, for example, may simply not have the capability to share the required data and are likely to be most reluctant to share commercially sensitive data necessary for “smarter risking”, data-based calculations of traders’ likely compliance to reduce the need to check them.

And the creation of a common all-Ireland veterinary and phytosanitary zone (SPS), seen as among the most attractive, deliverable and negotiable options, raises “many of the challenges of the backstop” – “democratic accountability, east/west implications , and implications for international trade”.

The common SPS zone would require customs declarations on all cross-border goods and checks on the Irish Sea.

Significantly, however, both the DUP and Boris Johnson have indicated some support for the idea in the last two days.

The idea of using mobile SPS checks away from the Border was seen as “attracting very poor negotiability” and as the “most untenable facilitation”, impractical, and involving high security risks. And the report warns that as most food consignments are chilled or frozen, physical inspection would require unloading “to maintain the integrity of the cold chain, this would need to take place in a temperature controlled fixed facility.” All over the countryside?

EU regulations mandate SPS inspections “at the point of entry”.

Onboard vehicle technology which could track the location, weight and temperature of goods is also considered risky if a lorry might suddenly be taken out of service and goods offloaded into a non-registered vehicle.

Physical goods checks through mobile units could take weeks and involve lengthy periods of quarantine, the report found. The units could also be vulnerable to “targeting” and staff could be at risk, the report said.

Assessments of the potential of artificial intelligence and the internet of things, a new “border code” set of rules for all, and new industry-based regulatory approaches need further work, the report warns.

Trusted traders “Trusted trader” schemes, widely touted as being capable of removing the necessity for checks on the bulk of regular trade, are seen as having potential but requiring elaborate administration.

But even if adopted, the necessity of border checks on a minority of goods, and particularly of SPS controls, mean that border-based controls cannot simply be wished away – a challenge not just for the UK authorities, but for those in the South who have long insisted that the UK’s alternative arrangements are simply not practical or remotely ready for use.

With little prospect of any viable UK backstop alternative emerging ahead of a UK election, and the prospect of a no-deal Brexit looming larger, Dublin is understood to be quietly but intensively preparing for the inevitability of some form of hard border controls.