On New Year’s Day I went for a swim off Broad Haven beach in Pembrokeshire. The water was 10.3ºC: pretty good agony, but not as bad as the cold on the soles of my feet as I changed on the icy sand. Cold-water swimming is on the up — 700 people took part in the Boxing Day swim in nearby Tenby, the most in its 46-year history. I can see the attraction. A freezing sea is a tremendous hangover cure. Once back indoors you glow as the blood, which rushes to the core of your body to prevent heat loss underwater, races back to your skin. A cold swim is like a hair shirt. After the indulgence of Christmas and New Year’s Eve, self-inflicted pain is a fine mental corrective. The Romans understood this in their baths, where they entered the caldarium, tepidarium and frigidarium, in that order; boiling, warm, freezing. Cold is the new hot.

Walking along the Pembrokeshire cliffs, I stumbled across one of the great sights of British nature. Guillemots lay their eggs and rear their young here from March to July and spend the rest of their lives at sea. But in occasional years, they return in midwinter. And here they were, squeezed on top of Stack Rocks — a pair of limestone skyscrapers 50 yards out to sea — squawking their heads off. It’s called the winter dance. The late Ronald Lockley, king of Pembrokeshire naturalists, thought it was a mating ritual brought on by ‘the general nervous stimulation of the breeding season’. I know humans who feel the same way. Guillemots don’t mate during the dance. And they stay for only a moment; by the time we’d retraced our steps they’d gone. I like to put their return down to homesickness. Or a ritual coinciding with the shortest days of the year: like Christmas, Saturnalia and swimming on New Year’s Day.

Over New Year, friends in Wales were discussing Christmas presents. One teased her boyfriend for suggesting a ‘didactic present’: a Fitbit, with the implication that she needed to take exercise. Another didactic present suggestion — driving lessons — went down just as badly. I feel a related aversion to self-improving New Year resolutions such as giving up drink, sugar or fat. They masquerade as self-sacrifice but are really vain health kicks. I admire anyone who selflessly resolves to buy more drink, sugar and fat for themselves and their friends and raise jolliness levels in the bleak midwinter.

In that spirit, I salute Nicholas Soames, who’s addressing the Drink Tank, a political discussion group, in a Pimlico pub in a fortnight. The Drink Tank was founded on the principle that there is no extended political discussion that can’t be relieved by the judicious application of alcohol. Soames has given up drink. And yet he is prepared to spend a dry evening watching hacks and political groupies get increasingly inebriated while he discusses the more brain-crunching aspects of modern politics. That’s what I call self-sacrifice.

Last week I took the Eurostar to the Gare du Nord in Paris. We had lunch next to the station at the Terminus Nord brasserie, unchanged since 1925. The art deco clock on the wall has literally stopped, and everything else is frozen in the world of Fred Astaire, from the mosaic floor to the mirrored walls, to murals of dancers in tails and flapper dresses. But my God the Gare du Nord is a dump. It has a fine 1863 iron-and-glass train shed, with a classical facade lined with statues of handsome women, representing destinations from Calais to the heart-stirring battlefields of Arras and Dunkirk. The station is now a wreck, haunted by lost souls, homeless, drunk and begging. In the station loos, a graffito reads, ‘Il y’a meilleurs toilettes en prison qu’ici.’ I bet French prisons also have better check-in systems than Eurostar’s at Gare du Nord. Hundreds of travellers are crammed into a small glass box with expansive views of empty swaths of the station concourse, thinly scattered with badly lit sandwich bars and shops. Memo to the builders of the new Euston station — make it beautiful and use the space cleverly.

If you’re confused about how Brexit will turn out, try writing a book about it. I’ve got one coming out at the end of the month — called Summer Madness: How Brexit Split the Tories, Destroyed Labour and Divided the Country — and I’ve already had to update the draft after Trump’s victory… again after the Italian referendum… and twice more after two by-elections. For your sake and mine, I wish you a happy, entirely uneventful new year.