Imagine you had never seen a car in real life. You’ve heard of them. You know they exist in America and possibly other countries too. You’ve perhaps seen a grainy black and white photograph of a Model T Ford, and maybe an artist’s impression of a 1950s concept car, but you’ve never actually touched a car, sat in one, driven one. In your country, people stick with 18th century technology: covered wagons. You know where you are with covered wagons. Cars baffle you – they have no horses, what strange alchemy goes on within?

You decide to learn about cars, and the first thing you notice is that most cars are made of metal. Metal is heavy. You are no fool. You worry about the weight of a metal roof on your covered wagon and think, “How can this possibly be an improvement on what we have?”.

Then you learn to your horror that cars sometimes crash. Even though they have steering wheels, and brakes, accidents still happen. It just proves to you that steering wheels and brakes are useless. Your covered wagon has never crashed in three centuries. So why risk it?

A friend tells you that cars are a product of the scientific and industrial revolutions. So was Soviet tyranny. Therefore, you conclude, cars are instruments of tyranny. Never mind that Henry VIII and Edward Longshanks had covered wagons.

Cars still need drivers to decide where to go. A car without a good driver can get lost or cause an accident. Your covered wagon has had a long history of drivers, mostly from the same school, for hundreds of years. Focus on the driver, not the vehicle. Cars solve nothing.

That’s not the only problem. If you get stuck in the wilderness with a covered wagon, you can still use it as a tent. You can put the base of the wagon on its side as a windbreak. You can’t do that with a car. Cars lack versatility.

It’s hard to redesign a car once it is built. You can’t change a sports car into an off-road 4x4. But you can plane and sand and shave the planks on your wagon as you wish – every driver can customise it. Never mind that this also enables anyone to mis-cut and break it easily.

Let’s get back to that Model T Ford. You are smart. You’ve done your research. You might well be a Professor of Wagon Wheels at a prestigious English University. You know that the Model T Ford had a gravity-fed fuel system, which meant that when the fuel was low it could not go up steep hills except in reverse. Your covered wagon doesn’t need to do this. You conclude that cars are bad. The fact that modern cars have fuel pumps is irrelevant, because you’ve never heard about those.

Besides, cars are just not the way things are done in this country. We have covered wagons. Our ancestors defeated half the world with covered wagons, and there is something suspiciously foreign about cars. Even the vocabulary – ‘chassis’, ‘carburettor’, ‘chauffeur’, ‘garage’ – is a bit French. Never mind that cars are also used by almost all our former colonies, or that we designed and built them, because we realised how useful they are.

Then someone with a big grin and a penchant for invading Iraq comes along and says that the wagon needs modernising.

He’s seen that some cars have go-faster stripes. Others have electric windows. He decides to put go-faster stripes and electric windows on the covered wagon. Progress! Unfortunately, the go-faster stripes don’t actually make it go faster, and the electric windows have an unintended consequence: because we didn’t fit an engine, like a proper car, the battery has to be charged by a cycle generator. Proves progress is elusive.

That, ladies and gentlemen, is about the state of constitutional reform debate in the UK today. It is all about tinkering with the wagon and criticising the American Model T Ford, ignoring the fact that we once built and exported Morris Minors and Land Rovers, and that Teslas and Ferraris exist.

Of course, there are genuine concerns about cars. Pollution is perhaps the most pressing concern. That is why many countries are phasing out internal combustion engines in favour of all-electric cars in the coming years, just as some countries have phased out First Past the Post in favour of all-proportional electoral systems.

It would be wrong to see cars the one-size-fits-all solution. There are genuine concerns, from pollution to urban sprawl. For some purposes, trains, trams or bikes are better. But not covered wagons. There is no transport application for which a covered wagon is today the best choice.

In the same way, constitutions are not the answer to everything. They don’t replace the need for effective parties, responsible leaders and good policies. But there’s no case in which the ramshackle crate of the eighteenth-century Hanoverian coach is better than a proper modern written Constitution.

This column welcomes questions from readers

Political analyst, and former Tory head of communications, Andy MacIver, is the guest on the TNT show at 7pm on Wednesday