I will always remember the day they inaugurated Donald Trump President of the United States. I greeted the dawn of the age of American Carnage leaning queasily at the bar of a pub in Newtownbutler, County Fermanagh, knocking back Imodium tablets with gulps of Guinness, watched out of the corners of their eyes by suspicious and disgusted patrons. If you can imagine that record-scratch “you may be wondering how I came to be in this situation” moment, let me explain.

Like much of the territory along the border, Monaghan bears its scars

I’ve always been interested in borders. Donald Trump thinks militarised borders and high walls are “beautiful”, but I don’t agree. They’re some of the ugliest, meanest environments humanity has created. I’ve had two ideas of writing a book about borders in the last few years. My first thought was to write about walking along the length of the Irish border, adrift and uncertain like the border itself in the Brexit world imposed by my fellow Englishmen. The thought was not a unique one – Garrett Carr published The Rule of the Land later in 2017, having cheated by thinking up the idea a bit earlier and being born not far from the border himself. I broadened the idea to covering more of Europe, looking at the century since Versailles and Trianon, and I’m still working on it. My work in walking a fair chunk of the distance from Carlingford to Muff will not have been wasted.

I was staying in the market town of Monaghan, in that part of the historic province of Ulster which is in the Republic of Ireland. Like much of the territory along the border, Monaghan bears its scars – there is an illuminated column to commemorate the seven people who died in the town in a co-ordinated Loyalist bombing offensive in 1974. Although Carr’s book is lyrical, there is a bleak book to be written about the Irish border – the masked men shuttling across in stolen cars under cover of darkness and the isolated farmhouses, such as the one Arlene Foster grew up on, where big dogs and shotguns failed to dispel constant dread.

Monaghan is near one of the most peculiar stretches of the border. Something weird happens on the N54 road towards Cavan. The paint on the road flips to white, signs start being in miles per hour and you’re suddenly on the A3. In this short stretch of road, the motorist crosses an international border four times in about four miles, ending up back south of the border at the end of it. However, ascribing a compass point to the border at this point is misleading, because it weaves crazily around what geographers call the “Drummully Polyp” – Ireland having a surplus of place names, it is also “Coleman’s Island” and “Connons”. It is a mad whorl of County Monaghan intruding into County Fermanagh, connected to the rest of the county only at a few unbridged yards of the Finn River. Its shape is so irregular that it also creates a de facto cut-off bit of Fermanagh only accessible from Monaghan. It made no difference until 1920, when it also became an international boundary. It could have been even more absurd, but the British and Irish decided to make the N54 a “concession road” so that you could drive from Cavan to Monaghan without exporting, importing, re-exporting and re-importing the contents of a van.

So it was that I decided to walk around the Polyp on 20 January 2017. I had saved this particular border anomaly treat for a day when I would need some cheering up. It was a refreshing, chilly day, and I set out cold-cheeked and smiling into the Irish countryside, looking forward to a double-figure number of border crossings on my rural ramble.

Any farmer observing the scene of squalor I left will have assumed that a sick cow had been driven along the lane

The border is virtually invisible, and it was only by constant monitoring of my position on my phone that I knew which country I was in from minute to minute. It was another reminder that land borders make different things important – the European Parliament’s ban on roaming charges was a boon to border residents across the continent. Everything went well until I had reached the Polyp. Intense pain started to wrack my gut as something I had eaten disagreed with me as strongly as I disagreed with the soon to be President. I was on an open road, so there was nowhere to hide. I hobbled, clenched and sweating, along my chosen route, for what else could I do? The Polyp is farm country. There were no pubs, no shops, and given its history the border is the least likely part of rural Ireland to extend lavatorial hospitality to a desperate traveller. Finally I came to a turn, and a lane that was more of an indentation running behind a hedgerow. Relief came quickly and spectacularly. Any farmer observing the scene of squalor I left will have assumed that a sick cow had been driven along the lane, rather than a human being. It was degrading and shaming, but purgative. I had drained the swamp, or so I thought.

I continued on my way, white faced but trying for the jaunty mien of a sophisticate who could have nothing to do with anything so horrible. But only a couple of crossings later, my gut felt as twisted as the border I was treating so casually. Thank God, in the middle of nowhere – I think in Northern Ireland, but they preferred Euros – I stumbled across a bakery who let me use their facilities and sold me some comfortingly stodgy cakes.

At this point, I ditched my more ambitious ideas about the walk and used the moment of intestinal clarity to head for the nearest significant settlement, which was Newtownbutler. I made it just in time before the chemist closed so I could buy some Imodium, and then go to the pub to watch the inauguration. Everything hurt – my legs, my gut, my head – so it was time for a drink. Alcohol’s antiseptic, right? I could not keep up the pose for long at the bar until I turned green and had to rush for the toilet. What went on as I was miserably ensconced in a cubicle was so revolting that when another man came into the toilets, he exclaimed “Aw, fook,” and walked out again, and the threshold for that in a country pub is pretty high. I blame Trump.

There were two televisions in the bar room, one showing the broadcast from Washington and the other showing a horse race – racing on one channel, racism on the other. I saw it through, Guinness and Imodium settling my stomach until I was sure I was fit to get a taxi all the way back to Monaghan. By that stage Donald Trump was President. Apparently, after hearing the speech I listened to in such discomfort in Newtownbutler, George W Bush turned to Hillary Clinton and said, “Well, that was some weird shit.” George, you have no idea.