The past few days on the campaign trail would have rattled most would-be prime ministers. Not Boris Johnson, it seems.

In an interview with an ITV reporter yesterday, Johnson refused to look at a photo of a sick child lying on the floor of a hospital in Leeds, before entering into a furore over false claims that a Tory adviser was punched by a Labour activist.

Meanwhile, Northern Ireland returned to centre stage of the Brexit debate, casting doubt on Johnson’s ability to ‘Get Brexit Done’ following two of the most important government leaks since Operation Yellowhammer revealed the government’s plans for food shortages in the event of a no-deal.

The first document, leaked from the Treasury and revealed by Labour on Friday, is titled Northern Ireland Protocol: Unfettered Access to the UK Internal Market. It “drives a coach and horses” through Johnson’s claim there will be no Irish Sea border after Brexit, according to Jeremy Corbyn.

The Labour leader said the documents proved there would be customs checks in both directions between Great Britain and Northern Ireland, a direct contradiction of Johnson’s previous claims.

General election: what the manifestos say on issues affecting food and drink

The document warned custom checks would be “highly disruptive” to Northern Ireland’s economy, leaving 98% of Northern Irish exporters struggling “to bear this cost”.

The second, a DExEU report seen by the Financial Times on Monday, said UK officials believed a new Northern Ireland customs arrangement was unlikely to be ready by December 2020, making Johnson’s Brexit deadline unlikely.

The document called it a “major strategic, political and operational challenge”.

It leaves the Northern Ireland food and drink sector feeling decidedly nervous. And rightly so.

Johnson has shown he is willing to throw Northern Ireland under the bus so long as it delivers him the Brexit he desires. His premiership so far has been built on the promise he will implement a Brexit deal by December 2020, and his record suggests he will not let Northern Ireland get in the way.

The documents released this week prove he has now betrayed promises made to the DUP conference last year that his withdrawal agreement would not lead to a trade barrier in the Irish Sea.

DUP leader Arlene Foster accused him of duplicity yesterday on the BBC’s Today programme. “Once bitten, twice shy. We will certainly be looking for the detail of what this [Brexit] is going to look like.”

Unfortunately for Northern Irish exporters, the opportunity to be “twice shy” may not be forthcoming.

With the latest polls showing a Conservative lead of 10 points for this week’s election and even Jon Ashworth, shadow health secretary, calling Labour’s prospects “dire” in a leaked phone call, a Johnson-led majority seems the most probable outcome.

In any case, he is unlikely to look across the Irish Sea for support.

And if the DUP were unable to restrain Johnson while they held a supporting role in the UK’s previous government, their predicament is unlikely to improve once they join those out in the shadows looking in.

Northern Ireland’s food sector yearns for the opportunity to engage with government, but, come Friday, it is likely find the government’s doors more firmly closed than ever before.