Having returned from a fortnight’s break, I wonder if we get holidays all wrong. In northern Europe, the custom is that you head south to spend time on the beach. But equally, there is such a thing as too damned hot, especially if, like me, you have a healthy dose of Celtic ancestry.

To avoid this, you need to study what is called the ‘wet-bulb temperature’. This is a measure of temperature which accounts for the cooling effect of evaporation. At 100 per cent relative humidity, the wet-bulb temperature is equal to the dry-bulb temperature shown on weather forecasts. At lower humidity the wet-bulb temperature is lower, owing to evaporative cooling, a mechanism all humans other than Prince Andrew depend on to reduce their body temperature. This explains why I can wander around Phoenix comfortably at 100°F, while I find London at 90° uninhabitable.

It’s the wet-bulb component of temperature that environmentalists should be eager to warn us about. Above a wet-bulb temperature of 90°, even a fit, well-hydrated human sitting by a fan cannot really function. Add a few degrees and they die. We should consider humidity before deciding where to go on holiday. But we don’t.

Another reason not to head south next summer is something we barely think about at all: hours of daylight. True, southerly climes are warmer – but it’s dark after dinner. There’s virtually no twilight, even in southern France, and you’re left in darkness with the din of mopeds and barking dogs. By contrast, go to Scandinavia or Scotland in June or July and it will probably rain a bit, but with 18+ hours of daylight to play with, who cares?

My final holiday tip is to avoid uber-famous cities, which are overcrowded and expensive at peak times. What determines visitor numbers to any city is largely arbitrary, but there is an insane winner-takes-all effect, which means second-rank cities are hugely undervisited. Why does nobody go on holiday to Germany? In part because their cities have few of the landmark features people want. Try completing the sentence: ‘Come to Dusseldorf and see the…’

By contrast Paris has the Mona Lisa and a big tower; London has a really big clock, and a bridge that opens, and buses which foreigners find odd. Combine this with young people’s weird compulsion to take selfies in front of famous places and I fear we shall see the over-concentration of tourism only getting worse.

But this mechanism does present opportunities for creative regeneration. It needn’t be a Guggenheim or a Burj Khalifa. The Japanese town of Kanazawa was widely attacked for spending more than $200,000 of Covid relief funds on a 45ft-long statue of a squid. It now turns out that, by raising visitor numbers, the squid has already paid for itself 22 times over and has created 38 jobs.

One of the most ingenious branding ideas of recent years was the naming of the ‘North Coast 500’ which took 516 miles of scenic roads around the far north of Scotland and turned them into a destination and hence a bucket-list item. The High Line in New York is a similar piece of genius, transforming a disused railway line through a neglected part of Manhattan into an aerial parkland walkway.

Given the returns on some of these efforts, it’s a shame they aren’t more common. I suspect that’s because they involve a degree of eccentricity, which pains conventional decision makers. Yet it’s the weirder ideas that work best. I once travelled to Newhaven solely to see its wonderfully bizarre memorial to Ho Chi Minh. It seems that as well as being a son of a bitch with blue balls, crabs and the seven-year itch (as they sang in Full Metal Jacket), Uncle Ho briefly worked as a pastry chef on the ferry to Dieppe.